DataFrame.apply
Apply a function to each element or along a specified axis of a DataFrame.
danfo.DataFrame.apply(callable, options)
Parameters
Type
Description
Default
callable
Function
Function to apply to each column or row
options
Object
axis: 0 or 1. If 0, compute the power column-wise, if 1, row-wise
{axis: 1}
Examples
Apply a function along default axis 1 (columns)
Note that the specified function passed to
apply will be called with an array of the values across the specified axis.Node
Browser
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const dfd = require("danfojs-node")
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let data = [[1, 2, 3], [4, 5, 6], [20, 30, 40], [39, 89, 78]]
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let cols = ["A", "B", "C"]
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let df = new dfd.DataFrame(data, { columns: cols })
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function sum_vals(col) {
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return col.reduce((a, b) => a + b, 0);
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}
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let df_new = df.apply(sum_vals, { axis: 1 })
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df_new.print()
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1
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Output
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╔═══╤═════╗
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║ 0 │ 6 ║
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╟───┼─────╢
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║ 1 │ 15 ║
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╟───┼─────╢
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║ 2 │ 90 ║
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╟───┼─────╢
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║ 3 │ 206 ║
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╚═══╧═════╝
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Apply a function along axis 0 (row)
Node
Browser
1
const dfd = require("danfojs-node")
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let data = [[1, 2, 3], [4, 5, 6], [20, 30, 40], [39, 89, 78]]
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let cols = ["A", "B", "C"]
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let df = new dfd.DataFrame(data, { columns: cols })
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function sum_vals(col) {
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return col.reduce((a, b) => a + b, 0);
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}
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let df_new = df.apply(sum_vals, { axis: 0 })
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df_new.print()
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1
Copied!
Output
1
╔═══╤═════╗
2
║ A │ 64 ║
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╟───┼─────╢
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║ B │ 126 ║
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╟───┼─────╢
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║ C │ 127 ║
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╚═══╧═════╝
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Last modified 3mo ago