Danfo.js
Danfo.js
Getting Started
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Getting Started

Installation guides for Node and Browser based environments, including a quick 10 minute walk through of danfo.js

Installation

There are two ways to get danfo.js. We built an optimized and fast version for node.js and its available under the danfojs-node namespace. To install it via npm, you can do the following:

npm install danfojs-node

You can also install and use it in the browsers by using the CDN below:

<script src="https://cdn.jsdelivr.net/npm/danfojs@0.1.2/dist/index.min.js"></script>
​

To play with Danfo.js in a Notebook-like environment without doing an installation, use Dnotebooks here​

10 minutes to danfo.js

This is a short introduction to danfo.js, and its flow is adapted from the official 10 minutes to Pandas​

We will show you how to use danfo.js in both browser environment and Node.js environment. Most functions except plotting which require a DOM works the same way in both environments.

Node
Browser
Node
const dfd = require("danfojs-node")
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
      
      //danfo is exposed on dfd namespace 
      s = new dfd.Series([1,2,3,4,5]) 
​
    </script>
​
</body>
​
</html>

Object creation

Creating a Series by passing a list of values, letting danfo.js create a default integer index:

Node
Browser
Node
s = new dfd.Series([1, 3, 5, undefined, 6, 8])
s.print()
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
        s = new dfd.Series([1, 3, 5, undefined, 6, 8])
        s.print()
​
    </script>
​
</body>
​
</html>
//output
╔═══╤══════════════════════╗
║   │ 0                    ║
╟───┼──────────────────────╢
║ 0 │ 1                    ║
╟───┼──────────────────────╢
║ 1 │ 3                    ║
╟───┼──────────────────────╢
║ 2 │ 5                    ║
╟───┼──────────────────────╢
║ 3 │ NaN                  ║
╟───┼──────────────────────╢
║ 4 │ 6                    ║
╟───┼──────────────────────╢
║ 5 │ 8                    ║
╚═══╧══════════════════════╝

Creating a Series from a tensor

Node
Browser
Node
const dfd = require("danfojs-node")
const tf = require("@tensorflow/tfjs-node")
​
​
let tensor_arr = tf.tensor([12,34,56,2])
let s = new dfd.Series(tensor_arr)
s.print()
​
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <script src="https://cdn.jsdelivr.net/npm/@tensorflow/tfjs@latest"> </script>
​
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
        let tensor_arr = tf.tensor([12,34,56,2])
        let s = new dfd.Series(tensor_arr)
        s.print()
​
    </script>
​
</body>
​
</html>
╔═══╤══════════════════════╗
║   │ 0                    ║
╟───┼──────────────────────╢
║ 0 │ 12                   ║
╟───┼──────────────────────╢
║ 1 │ 34                   ║
╟───┼──────────────────────╢
║ 2 │ 56                   ║
╟───┼──────────────────────╢
║ 3 │ 2                    ║
╚═══╧══════════════════════╝

Creating a DataFrame by passing a JSON object:

Node
Browser
Node
const dfd = require("danfojs-node")
​
​
json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
            { A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
            { A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
            { A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
​
df = new dfd.DataFrame(json_data)
df.print()
​
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
         json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
            { A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
            { A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
            { A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
​
        df = new dfd.DataFrame(json_data)
        df.print()
         
    </script>
</body>
​
</html>
​

Creating a DataFrame from a 2D tensor

Node
Browser
Node
const dfd = require("danfojs-node")
const tf = require("@tensorflow/tfjs-node")
​
​
let tensor_arr = tf.tensor2d([[12, 34, 2.2, 2], [30, 30, 2.1, 7]])
let df = new dfd.DataFrame(tensor_arr, {columns: ["A", "B", "C", "D"]})
df.print()
df.ctypes.print()
​
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
         json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
            { A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
            { A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
            { A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
​
        df = new dfd.DataFrame(json_data)
        df.print()
         
    </script>
</body>
​
</html>
​
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 │ D                 ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ 12                │ 34                │ 2.20000004768...  │ 2                 ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ 30                │ 30                │ 2.09999990463...  │ 7                 ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝
​
╔═══╤══════════════════════╗
║   │ 0                    ║
╟───┼──────────────────────╢
║ A │ int32                ║
╟───┼──────────────────────╢
║ B │ int32                ║
╟───┼──────────────────────╢
║ C │ float32              ║
╟───┼──────────────────────╢
║ D │ int32                ║
╚═══╧══════════════════════╝

Creating a DataFrame by passing a dictionary of objects with the same length

Node
Browser
Node
const dfd = require("danfojs-node")
​
​
dates = new dfd.date_range({ start: '2017-01-01', end: "2020-01-01", period: 4, freq: "Y" })
​
console.log(dates);
​
obj_data = {'A': dates,
            'B': ["bval1", "bval2", "bval3", "bval4"],
            'C': [10, 20, 30, 40],
            'D': [1.2, 3.45, 60.1, 45],
            'E': ["test", "train", "test", "train"]
            }
​
df = new dfd.DataFrame(obj_data)
df.print()
​
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
        dates = new dfd.date_range({ start: '2017-01-01', end: "2020-01-01", period: 4, freq: "Y" })
​
        console.log(dates);
        
        obj_data = {'A': dates,
                    'B': ["bval1", "bval2", "bval3", "bval4"],
                    'C': [10, 20, 30, 40],
                    'D': [1.2, 3.45, 60.1, 45],
                    'E': ["test", "train", "test", "train"]
                    }
        
        df = new dfd.DataFrame(obj_data)
        df.print()
         
    </script>
</body>
​
</html>
​
//output in console
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 │ D                 │ E                 ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ 1/1/2017, 1:0...  │ bval1             │ 10                │ 1.2               │ test              ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ 1/1/2018, 1:0...  │ bval2             │ 20                │ 3.45              │ train             ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ 1/1/2019, 1:0...  │ bval3             │ 30                │ 60.1              │ test              ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ 1/1/2020, 1:0...  │ bval4             │ 40                │ 45                │ train             ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝
​

The columns of the resulting DataFrame have different dtypes.

df.ctypes.print()
//output
╔═══╤══════════════════════╗
║   │ 0                    ║
╟───┼──────────────────────╢
║ A │ string               ║
╟───┼──────────────────────╢
║ B │ string               ║
╟───┼──────────────────────╢
║ C │ int32                ║
╟───┼──────────────────────╢
║ D │ float32              ║
╟───┼──────────────────────╢
║ E │ string               ║
╚═══╧══════════════════════╝

Creating a DataFrame by passing an array of arrays. Index and column labels are automatically generated for you.

Node
Browser
Node
const dfd = require("danfojs-node")
​
arr_data = [["bval1", 10, 1.2, "test"],
            ["bval2", 20, 3.45, "train"],
            ["bval3", 30, 60.1, "train"],
            ["bval4", 35, 3.2, "test"]]
​
df = new dfd.DataFrame(arr_data)
df.print()
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
        arr_data = [["bval1", 10, 1.2, "test"],
            ["bval2", 20, 3.45, "train"],
            ["bval3", 30, 60.1, "train"],
            ["bval4", 35, 3.2, "test"]]
​
        df = new dfd.DataFrame(arr_data)
        df.print()
         
    </script>
</body>
​
</html>
​
//output in console
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ 0                 │ 1                 │ 2                 │ 3                 ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ bval1             │ 10                │ 1.2               │ test              ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ bval2             │ 20                │ 3.45              │ train             ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ bval3             │ 30                │ 60.1              │ train             ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ bval4             │ 35                │ 3.2               │ test              ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝
​

Viewing data

Here is how to view the top and bottom rows of the frame above:

df.head(2).print()
df.tail(2).print()
//output from head
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ 0                 │ 1                 │ 2                 │ 3                 ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ bval1             │ 10                │ 1.2               │ test              ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ bval2             │ 20                │ 3.45              │ train             ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝
​
​
//output from tail
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ 0                 │ 1                 │ 2                 │ 3                 ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ bval3             │ 30                │ 60.1              │ train             ║
╟───┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ bval4             │ 35                │ 3.2               │ test              ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝

Display the index, columns:

JavaScript
Browser
JavaScript
const dfd = require("danfojs-node")
​
dates = new dfd.date_range({ start: '2017-01-01', end: "2020-01-01", period: 4, freq: "Y" })
​
​
obj_data = {'A': dates,
            'B': ["bval1", "bval2", "bval3", "bval4"],
            'C': [10, 20, 30, 40],
            'D': [1.2, 3.45, 60.1, 45],
            'E': ["test", "train", "test", "train"]
            }
​
df = new dfd.DataFrame(obj_data)
​
console.log(df.index);
console.log(df.columns);
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
​
       dates = new dfd.date_range({ start: '2017-01-01', end: "2020-01-01", period: 4, freq: "Y" })
​
​
        obj_data = {'A': dates,
                    'B': ["bval1", "bval2", "bval3", "bval4"],
                    'C': [10, 20, 30, 40],
                    'D': [1.2, 3.45, 60.1, 45],
                    'E': ["test", "train", "test", "train"]
                    }
        
        df = new dfd.DataFrame(obj_data)
        
        console.log(df.index);
        console.log(df.columns);
         
    </script>
</body>
​
</html>
​
//output
[ 0, 1, 2, 3 ]
[ 'A', 'B', 'C', 'D', 'E' ]

​DataFrame.tensor returns a Tensorflow tensor representation of the underlying data. Note that Tensorflow tensors have one dtype for the entire array, while danfo DataFrames have one dtype per column.

For df, our DataFrame of all floating-point values, DataFrame.tensoris fast and doesn’t require copying data.

Node
Browser
Node
const dfd = require("danfojs-node")
​
​
json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
{ A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
{ A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
{ A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
​
df = new dfd.DataFrame(json_data)
​
console.log(df.tensor);
//or
df.tensor.print()
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
    
        json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
        { A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
        { A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
        { A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
        
        df = new dfd.DataFrame(json_data)
        
        console.log(df.tensor);
        //or
        df.tensor.print()
        
    </script>
</body>
​
</html>
​
//output
​
Tensor {
  kept: false,
  isDisposedInternal: false,
  shape: [ 4, 4 ],
  dtype: 'float32',
  size: 16,
  strides: [ 4 ],
  dataId: {},
  id: 0,
  rankType: '2'
}
​
Tensor
    [[0.4612, 4.2828302, -1.5089999, -1.1352  ],
     [0.5112, -0.22863 , -3.39059  , 1.1632   ],
     [0.6911, -0.82863 , -1.5059   , 2.1352   ],
     [0.4692, -1.28863 , 4.5058999 , 4.1631999]]

Note

​DataFrame.tensor does not include the index or column labels in the output.

​describe() shows a quick statistic summary of your data:

Node
Browser
Node
const dfd = require("danfojs-node")
​
​
json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
{ A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
{ A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
{ A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
​
df = new dfd.DataFrame(json_data)
​
df.describe().print()
​
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
    
        json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
                    { A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
                    { A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
                    { A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
        
        df = new dfd.DataFrame(json_data)
        
        df.describe().print()
        
    </script>
</body>
​
</html>
​
//output in console
​
╔════════╤═══════════════════╤═══════════════════╤═══════════════════╤═══════════════════╗
║        │ A                 │ B                 │ C                 │ D                 ║
╟────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ count  │ 4                 │ 4                 │ 4                 │ 4                 ║
╟────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ mean   │ 0.533175          │ 0.484235          │ -0.474898         │ 1.5816            ║
╟────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ std    │ 0.107543          │ 2.569317          │ 3.437147          │ 2.200545          ║
╟────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ min    │ 0.4612            │ -1.28863          │ -3.39059          │ -1.1352           ║
╟────────┼───────────────────┼───────────────────┼───────────────────┼───────────────────╢
║ median │ 0.4902            │ -0.52863          │ -1.50745          │ 1.6492            ║
╚════════╧═══════════════════╧═══════════════════╧═══════════════════╧═══════════════════╝

Sorting by values (Defaults to ascending):

Node
Browser
Node
const dfd = require("danfojs")
​
let data = [{ "A": [-20, 30, 47.3] },
            { "B": [34, -4, 5, 6] },
            { "C": [20, 2, 3, 30] }]
​
​
let df = new dfd.DataFrame(data)
df.sort_values({by: "C", inplace: true})
df.print()
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
    
        let data = [{ "A": [-20, 30, 47.3] },
            { "B": [34, -4, 5, 6] },
            { "C": [20, 2, 3, 30] }]
​
​
        let df = new dfd.DataFrame(data)
        df.sort_values({by: "C", inplace: true})
        df.print()
        
    </script>
</body>
​
</html>
​
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ 30                │ -4                │ 2                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ 47.3              │ 5                 │ 3                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ -20               │ 34                │ 20                ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

Selection

Getting

Selecting a single column, which yields a Series, equivalent to df.A:

Node
Browser
Node
const dfd = require("danfojs-node")
​
​
json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
{ A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
{ A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
{ A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
​
df = new dfd.DataFrame(json_data)
​
df['A'].print()
​
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.2/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
    
       
        json_data = [{ A: 0.4612, B: 4.28283, C: -1.509, D: -1.1352 },
                    { A: 0.5112, B: -0.22863, C: -3.39059, D: 1.1632 },
                    { A: 0.6911, B: -0.82863, C: -1.5059, D: 2.1352 },
                    { A: 0.4692, B: -1.28863, C: 4.5059, D: 4.1632 }]
                    
        df = new dfd.DataFrame(json_data)
        
        df['A'].print()
        
    </script>
</body>
​
</html>
​
//output
╔═══╤══════════════════════╗
║   │ A                    ║
╟───┼──────────────────────╢
║ 0 │ 0.4612               ║
╟───┼──────────────────────╢
║ 1 │ 0.5112               ║
╟───┼──────────────────────╢
║ 2 │ 0.6911               ║
╟───┼──────────────────────╢
║ 3 │ 0.4692               ║
╚═══╧══════════════════════╝

Selection by label

For getting a cross section using a label:

const dfd = require("danfojs")
​
let data = [{ "Name": ["Apples", "Mango", "Banana", "Pear"] },
           { "Count": [21, 5, 30, 10] },
           { "Price": [200, 300, 40, 250] }]
​
let df = new dfd.DataFrame(data, {index: ["a", "b", "c", "d"]})
df.print()
​
let sub_df = df.loc({rows: ["a", "c"]})
sub_df.print()
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ a │ Apples            │ 21                │ 200               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ b │ Mango             │ 5                 │ 300               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ c │ Banana            │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ d │ Pear              │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝
​
​
 Shape: (2,3) 
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ a │ Apples            │ 21                │ 200               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ c │ Banana            │ 30                │ 40                ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

Selecting on a multi-axis by label:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
            "Count": [21, 5, 30, 10],
             "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
df.print()
​
let sub_df = df.loc({ rows: [0,1], columns: ["Name", "Price"] })
sub_df.print()
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ Apples            │ 21                │ 200               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 5                 │ 300               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ Banana            │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Pear              │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝
​
​
 Shape: (2,2) 
​
╔═══╤═══════════════════╤═══════════════════╗
║   │ Name              │ Price             ║
╟───┼───────────────────┼───────────────────╢
║ 0 │ Apples            │ 200               ║
╟───┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 300               ║
╚═══╧═══════════════════╧═══════════════════╝

Showing label slicing, both endpoints are included:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
            "Count": [21, 5, 30, 10],
             "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
df.print()
​
let sub_df = df.loc({ rows: ["0:2"], columns: ["Name", "Price"] })
sub_df.print()
​
//before slicing
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ Apples            │ 21                │ 200               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 5                 │ 300               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ Banana            │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Pear              │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝
​
//after slicing
 Shape: (3,2) 
​
╔═══╤═══════════════════╤═══════════════════╗
║   │ Name              │ Price             ║
╟───┼───────────────────┼───────────────────╢
║ 0 │ Apples            │ 200               ║
╟───┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 300               ║
╟───┼───────────────────┼───────────────────╢
║ 2 │ Banana            │ 40                ║
╚═══╧═══════════════════╧═══════════════════╝

Selection by position

Select via the position of the passed integers:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
           "Count": [21, 5, 30, 10] ,
           "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
​
let sub_df = df.iloc({rows: [1,3]})
sub_df.print()
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 5                 │ 300               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Pear              │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

By integer slices:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
           "Count": [21, 5, 30, 10] ,
           "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
​
let sub_df = df.iloc({rows: ["1:3"]})
sub_df.print()
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 5                 │ 300               ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ Banana            │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Pear              │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

By lists of integer position locations:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
           "Count": [21, 5, 30, 10] ,
           "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
​
let sub_df = df.iloc({rows: [1,3], columns: [0,2]})
sub_df.print()
​
╔═══╤═══════════════════╤═══════════════════╗
║   │ Name              │ Price             ║
╟───┼───────────────────┼───────────────────╢
║ 1 │ Mango             │ 300               ║
╟───┼───────────────────┼───────────────────╢
║ 3 │ Pear              │ 250               ║
╚═══╧═══════════════════╧═══════════════════╝

For slicing rows explicitly:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
           "Count": [21, 5, 30, 10] ,
           "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
​
let sub_df = df.iloc({rows: ["2:3"], columns: [":"]})
sub_df.print()
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ Name              │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ Banana            │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Pear              │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

For slicing columns explicitly:

const dfd = require("danfojs-node")
​
let data = { "Name": ["Apples", "Mango", "Banana", "Pear"] ,
           "Count": [21, 5, 30, 10] ,
           "Price": [200, 300, 40, 250] }
​
let df = new dfd.DataFrame(data)
​
let sub_df = df.iloc({rows: [":"], columns: ["1:2"]})
sub_df.print()
​
╔═══╤═══════════════════╤═══════════════════╗
║   │ Count             │ Price             ║
╟───┼───────────────────┼───────────────────╢
║ 0 │ 21                │ 200               ║
╟───┼───────────────────┼───────────────────╢
║ 1 │ 5                 │ 300               ║
╟───┼───────────────────┼───────────────────╢
║ 2 │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────╢
║ 3 │ 10                │ 250               ║
╚═══╧═══════════════════╧═══════════════════╝

Boolean Querying/Filtering

Using a single column’s values to select data.

Node
Browser
Node
const dfd = require("danfojs-node")
​
let data = [[1, 2, 3], [4, 5, 6], [20, 30, 40], [39, 89, 78]]
let cols = ["A", "B", "C"]
​
let df = new dfd.DataFrame(data, { columns: cols })
df.print() //before query
​
let query_df = df.query({ "column": "B", "is": ">", "to": 5 })
query_df.print() //after query
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.1/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
    
       
       let data = [[1, 2, 3], [4, 5, 6], [20, 30, 40], [39, 89, 78]]
        let cols = ["A", "B", "C"]
        
        let df = new dfd.DataFrame(data, { columns: cols })
        df.print() //before query
        
        let query_df = df.query({ "column": "B", "is": ">", "to": 5 })
        query_df.print() //after query
        
    </script>
</body>
​
</html>
​
//before query
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ 1                 │ 2                 │ 3                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ 4                 │ 5                 │ 6                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ 20                │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ 39                │ 89                │ 78                ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝
​
//after query
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ 20                │ 30                │ 40                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ 39                │ 89                │ 78                ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

Selecting values from a DataFrame works on string columns:

let data = [{"A": ["Ng", "Yu", "Mo", "Ng"]},
            {"B": [34, 4, 5, 6]}, 
             {"C": [20, 20, 30, 40]}]
let df = new dfd.DataFrame(data)
​
df.print()
​
let query_df = df.query({ column: "A", is: "==", to: "Ng"})
query_df.print() //after query
​
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ Ng                │ 34                │ 20                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 1 │ Yu                │ 4                 │ 20                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 2 │ Mo                │ 5                 │ 30                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Ng                │ 6                 │ 40                ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝
​
//after query
​
╔═══╤═══════════════════╤═══════════════════╤═══════════════════╗
║   │ A                 │ B                 │ C                 ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 0 │ Ng                │ 34                │ 20                ║
╟───┼───────────────────┼───────────────────┼───────────────────╢
║ 3 │ Ng                │ 6                 │ 40                ║
╚═══╧═══════════════════╧═══════════════════╧═══════════════════╝

Adding a new column

Setting a new column automatically aligns the data by the indexes.

Node
Browser
Node
const dfd = require("danfojs-node")
​
let data = { "A": [30, 1, 2, 3] ,
             "B": [34, 4, 5, 6] ,
             "C": [20, 20, 30, 40] }
​
let df = new dfd.DataFrame(data)
df.print()
​
let new_col = [1, 2, 3, 4]
df.addColumn({ "column": "D", "value": new_col }); //happens inplace
​
df.print()
Browser
<!DOCTYPE html>
<html lang="en">
​
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <!--danfojs CDN -->
    <script src="https://cdn.jsdelivr.net/npm/danfojs@0.0.1.1/dist/index.min.js"></script>
    <title>Document</title>
</head>
​
<body>
​
    <script>
    
       
        let data = { "A": [30, 1, 2, 3] ,