66 lines
1.9 KiB
Markdown
66 lines
1.9 KiB
Markdown
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<!-- Note: This file is automatically generated from source code comments. Changes made in this file will be overridden. -->
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# Function map
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Create a new matrix or array with the results of a callback function executed on
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each entry of a given matrix/array.
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For each entry of the input, the callback is invoked with three arguments:
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the value of the entry, the index at which that entry occurs, and the full
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matrix/array being traversed. Note that because the matrix/array might be
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multidimensional, the "index" argument is always an array of numbers giving
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the index in each dimension. This is true even for vectors: the "index"
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argument is an array of length 1, rather than simply a number.
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## Syntax
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```js
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math.map(x, callback)
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```
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### Parameters
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Parameter | Type | Description
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--------- | ---- | -----------
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`x` | Matrix | Array | The input to iterate on.
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`callback` | Function | The function to call (as described above) on each entry of the input
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### Returns
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Type | Description
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---- | -----------
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Matrix | array | Transformed map of x; always has the same type and shape as x
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### Throws
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Type | Description
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---- | -----------
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## Examples
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```js
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math.map([1, 2, 3], function(value) {
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return value * value
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}) // returns [1, 4, 9]
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// The calling convention for the callback can cause subtleties:
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math.map([1, 2, 3], math.format)
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// throws TypeError: map attempted to call 'format(1,[0])' but argument 2 of type Array does not match expected type number or function or Object or string or boolean
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// [This happens because `format` _can_ take a second argument,
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// but its semantics don't match that of the 2nd argument `map` provides]
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// To avoid this error, use a function that takes exactly the
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// desired arguments:
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math.map([1, 2, 3], x => math.format(x)) // returns ['1', '2', '3']
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```
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## See also
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[filter](filter.md),
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[forEach](forEach.md),
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[sort](sort.md)
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