NumPy: index() function

numpy.core.defchararray.index() function

The numpy.core.defchararray.index() function work as find() function but raises ValueError when the substring is not found.
Calls str.index element-wise.

Version: 1.15.0

Syntax:

numpy.core.defchararray.index(a, sub, start=0, end=None)

Parameter:

Return value:

out : ndarray - Output array of ints. Returns -1 if sub is not found.

Note:

The 'chararray' class exists for backwards compatibility with Numarray, it is not recommended for new development. Starting from numpy 1.4, if one needs arrays of strings, it is recommended to use arrays of 'dtype' 'object_', 'string_' or 'unicode_', and use the free functions in the 'numpy.char' module for fast vectorized string operations.

Some methods will only be available if the corresponding string method is available in your version of Python.

The preferred alias for 'defchararray' is 'numpy.char'.

Example-1: numpy.index() function

>>> import numpy as np
>>> x = np.char.index('the quick brown fox jumps over the lazy dog', 'over the lazy dog', start=0, end=None)
>>> x
array(26)

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Example-2: numpy.index() function

>>> import numpy as np
>>> y = np.char.index('w3resource', 'u', start=0, end=None)
>>> y
array(6)

Pictorial Presentation:

Python - NumPy Code Editor:

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