NumPy strings.center()

The numpy.strings.center() function returns a copy of a string with its elements centered in a string of a specified length. Optional padding characters can be used to fill the remaining space.

Syntax

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numpy.strings.center(a, width, fillchar=' ')

Parameters

Parameter	Type	Description
`a`	array_like (StringDType, bytes_, or str_)	The input string or array of strings to be centered.
`width`	array_like (integer dtype)	The total length of the resulting string. If `width` is smaller than the original string length, the original string is returned unchanged.
`fillchar`	array_like (StringDType, bytes_, or str_), optional	The character used for padding. Default is a space (‘ ‘).

Return Value

Returns an ndarray containing strings that are centered within the specified width, padded using the specified character.

Examples

1. Centering a Single String with Default Padding

In this example, we center the string 'apple' within a width of 10 characters using spaces as the default padding character.

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import numpy as np

# Define the input string
fruit = np.array('apple', dtype='U')

# Center the string within a width of 10
result = np.strings.center(fruit, 10)

# Print the result
print("Centered String:", repr(result))

Output:

Centered String: array('  apple   ', dtype='<U10')

2. Centering Multiple Strings in an Array

We center multiple fruit names within a width of 12 characters using space padding.

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import numpy as np

# Define an array of fruit names
fruits = np.array(['apple', 'banana', 'cherry'], dtype='U')

# Center each string within a width of 12
result = np.strings.center(fruits, 12)

# Print the results
print("Centered Strings:")
print(repr(result))

Output:

Centered Strings:
array(['   apple    ', '   banana   ', '   cherry   '], dtype='<U12')

3. Using a Custom Padding Character

We use a custom character '-' instead of spaces for padding.

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import numpy as np

# Define an array of fruit names
fruits = np.array(['apple', 'banana', 'cherry'], dtype='U')

# Center each string with '-' as the padding character
result = np.strings.center(fruits, 12, fillchar='-')

# Print the results
print("Centered Strings with '-' padding:")
print(repr(result))

Output:

Centered Strings with '-' padding:
array(['---apple----', '---banana---', '---cherry---'], dtype='<U12')

4. Handling Strings Longer Than the Specified Width

If the width is smaller than the string length, the function returns the original string without modification.

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import numpy as np

# Define an array of fruit names
fruits = np.array(['apple', 'banana', 'cherry'], dtype='U')

# Center each string in a smaller width
result = np.strings.center(fruits, 4)

# Print the results
print("Strings when width is smaller than the string length:")
print(repr(result))

Output:

Strings when width is smaller than the string length:
array(['apple', 'banana', 'cherry'], dtype='<U6')

Since the width is smaller than the string length, no centering is applied, and the original strings are returned.

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NumPy strings.center() – Padding Around String