NumPy strings.isupper()

The numpy.strings.isupper() function checks whether all cased characters in a string array are uppercase and there is at least one character. If the condition is met, it returns True, otherwise False.

Syntax

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numpy.strings.isupper(x, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True)

Parameters

Parameter	Type	Description
`x`	array_like, with StringDType, bytes_ or str_ dtype	Input array containing string elements to check.
`out`	ndarray, None, or tuple of ndarray and None, optional	Optional output array where the result is stored. If None, a new array is created.
`where`	array_like, optional	Boolean mask specifying which elements to check. Elements where `where=False` retain their original value.
`casting`	str, optional	Defines the casting behavior when checking string cases.
`order`	str, optional	Memory layout order of the output array.
`dtype`	data-type, optional	Defines the data type of the output array.
`subok`	bool, optional	Determines if subclasses of ndarray are preserved in the output.

Return Value

Returns a boolean array indicating whether each string in the input array consists entirely of uppercase characters and contains at least one character. If the input is a scalar, a scalar boolean value is returned.

Examples

1. Checking Uppercase for a Single String

In this example, we check if a single string is entirely in uppercase.

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import numpy as np

# Define a single string
string = np.str_("HELLO")

# Check if the string is uppercase
result = np.strings.isupper(string)

# Print the result
print("Is the string uppercase?", result)

Output:

Is the string uppercase? True

2. Checking Uppercase for an Array of Strings

We check whether multiple strings in an array are uppercase.

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import numpy as np

# Define an array of strings
strings = np.array(["HELLO", "world", "PYTHON", "123", "UPPERlower"])

# Check if each string is uppercase
result = np.strings.isupper(strings)

# Print the results
print("Input strings:", strings)
print("Uppercase check:", result)

Output:

Input strings: ['HELLO' 'world' 'PYTHON' '123' 'UPPERlower']
Uppercase check: [ True False  True False False]

3. Using the `out` Parameter

Using an output array to store results instead of creating a new array.

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import numpy as np

# Define an array of strings
strings = np.array(["HELLO", "world", "PYTHON", "numpy"])

# Create an output array with the same shape
output_array = np.empty_like(strings, dtype=bool)

# Check uppercase and store the result in output_array
np.strings.isupper(strings, out=output_array)

# Print the results
print("Uppercase check stored in output array:", output_array)

Output:

Uppercase check stored in output array: [ True False  True False]

4. Using the `where` Parameter

Using a condition to check uppercase only for selected elements.

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import numpy as np

# Define an array of strings
strings = np.array(["HELLO", "WORLD", "Python", "numpy"])

# Define a mask (check uppercase only where mask is True)
mask = np.array([True, False, True, True])

# Compute uppercase check where mask is True
result = np.strings.isupper(strings, where=mask)

# Print the results
print("Uppercase check with mask:", result)

Output:

Uppercase check with mask: [ True False False False]

The uppercase check is applied only where mask=True. Other values retain their original state.

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NumPy strings.isupper() – Check if Each Element is Uppercase