Legacy fixed-width string functionality#

Legacy

This submodule is considered legacy and will no longer receive updates. This could also mean it will be removed in future NumPy versions. The string operations in this module, as well as the numpy.char.chararray class, are planned to be deprecated in the future. Use numpy.strings instead.

The numpy.char module provides a set of vectorized string operations for arrays of type numpy.str_ or numpy.bytes_. For example

>>> np.char.capitalize(["python", "numpy"])
array(['Python', 'Numpy'], dtype='<U6')
>>> np.char.add(["num", "doc"], ["py", "umentation"])
array(['numpy', 'documentation'], dtype='<U13')

The methods in this module are based on the methods in string

String operations#

`add`(x1, x2, /[, out, where, casting, order, ...])	Add arguments element-wise.
`multiply`(a, i)	Return (a * i), that is string multiple concatenation, element-wise.
`mod`(a, values)	Return (a % i), that is pre-Python 2.6 string formatting (interpolation), element-wise for a pair of array_likes of str or unicode.
`capitalize`(a)	Return a copy of `a` with only the first character of each element capitalized.
`center`(a, width[, fillchar])	Return a copy of a with its elements centered in a string of length width.
`decode`(a[, encoding, errors])	Calls `bytes.decode` element-wise.
`encode`(a[, encoding, errors])	Calls `str.encode` element-wise.
`expandtabs`(a[, tabsize])	Return a copy of each string element where all tab characters are replaced by one or more spaces.
`join`(sep, seq)	Return a string which is the concatenation of the strings in the sequence seq.
`ljust`(a, width[, fillchar])	Return an array with the elements of a left-justified in a string of length width.
`lower`(a)	Return an array with the elements converted to lowercase.
`lstrip`(a[, chars])	For each element in a, return a copy with the leading characters removed.
`partition`(a, sep)	Partition each element in a around sep.
`replace`(a, old, new[, count])	For each element in `a`, return a copy of the string with occurrences of substring `old` replaced by `new`.
`rjust`(a, width[, fillchar])	Return an array with the elements of a right-justified in a string of length width.
`rpartition`(a, sep)	Partition (split) each element around the right-most separator.
`rsplit`(a[, sep, maxsplit])	For each element in a, return a list of the words in the string, using sep as the delimiter string.
`rstrip`(a[, chars])	For each element in a, return a copy with the trailing characters removed.
`split`(a[, sep, maxsplit])	For each element in a, return a list of the words in the string, using sep as the delimiter string.
`splitlines`(a[, keepends])	For each element in a, return a list of the lines in the element, breaking at line boundaries.
`strip`(a[, chars])	For each element in a, return a copy with the leading and trailing characters removed.
`swapcase`(a)	Return element-wise a copy of the string with uppercase characters converted to lowercase and vice versa.
`title`(a)	Return element-wise title cased version of string or unicode.
`translate`(a, table[, deletechars])	For each element in a, return a copy of the string where all characters occurring in the optional argument deletechars are removed, and the remaining characters have been mapped through the given translation table.
`upper`(a)	Return an array with the elements converted to uppercase.
`zfill`(a, width)	Return the numeric string left-filled with zeros.

Comparison#

Unlike the standard numpy comparison operators, the ones in the char module strip trailing whitespace characters before performing the comparison.

`equal`(x1, x2)	Return (x1 == x2) element-wise.
`not_equal`(x1, x2)	Return (x1 != x2) element-wise.
`greater_equal`(x1, x2)	Return (x1 >= x2) element-wise.
`less_equal`(x1, x2)	Return (x1 <= x2) element-wise.
`greater`(x1, x2)	Return (x1 > x2) element-wise.
`less`(x1, x2)	Return (x1 < x2) element-wise.
`compare_chararrays`(a1, a2, cmp, rstrip)	Performs element-wise comparison of two string arrays using the comparison operator specified by cmp.

String information#

`count`(a, sub[, start, end])	Returns an array with the number of non-overlapping occurrences of substring `sub` in the range [`start`, `end`).
`endswith`(a, suffix[, start, end])	Returns a boolean array which is True where the string element in `a` ends with `suffix`, otherwise False.
`find`(a, sub[, start, end])	For each element, return the lowest index in the string where substring `sub` is found, such that `sub` is contained in the range [`start`, `end`).
`index`(a, sub[, start, end])	Like `find`, but raises `ValueError` when the substring is not found.
`isalpha`(x, /[, out, where, casting, order, ...])	Returns true for each element if all characters in the data interpreted as a string are alphabetic and there is at least one character, false otherwise.
`isalnum`(x, /[, out, where, casting, order, ...])	Returns true for each element if all characters in the string are alphanumeric and there is at least one character, false otherwise.
`isdecimal`(x, /[, out, where, casting, ...])	For each element, return True if there are only decimal characters in the element.
`isdigit`(x, /[, out, where, casting, order, ...])	Returns true for each element if all characters in the string are digits and there is at least one character, false otherwise.
`islower`(x, /[, out, where, casting, order, ...])	Returns true for each element if all cased characters in the string are lowercase and there is at least one cased character, false otherwise.
`isnumeric`(x, /[, out, where, casting, ...])	For each element, return True if there are only numeric characters in the element.
`isspace`(x, /[, out, where, casting, order, ...])	Returns true for each element if there are only whitespace characters in the string and there is at least one character, false otherwise.
`istitle`(x, /[, out, where, casting, order, ...])	Returns true for each element if the element is a titlecased string and there is at least one character, false otherwise.
`isupper`(x, /[, out, where, casting, order, ...])	Return true for each element if all cased characters in the string are uppercase and there is at least one character, false otherwise.
`rfind`(a, sub[, start, end])	For each element, return the highest index in the string where substring `sub` is found, such that `sub` is contained in the range [`start`, `end`).
`rindex`(a, sub[, start, end])	Like `rfind`, but raises `ValueError` when the substring sub is not found.
`startswith`(a, prefix[, start, end])	Returns a boolean array which is True where the string element in `a` starts with `prefix`, otherwise False.
`str_len`(x, /[, out, where, casting, order, ...])	Returns the length of each element.

Convenience class#

`array`(obj[, itemsize, copy, unicode, order])	Create a `chararray`.
`asarray`(obj[, itemsize, unicode, order])	Convert the input to a `chararray`, copying the data only if necessary.
`chararray`(shape[, itemsize, unicode, ...])	Provides a convenient view on arrays of string and unicode values.