NumPy strings.equal() – If Two String Arrays are Equal

NumPy strings.equal()

The numpy.strings.equal() function performs an element-wise comparison between two input arrays of strings and returns a boolean array indicating whether corresponding elements are equal.

Syntax

numpy.strings.equal(x1, x2, /, out=None, *, where=True, casting='same_kind', order='K', dtype=None, subok=True)

Parameters

Parameter	Type	Description
x1, x2	array_like	Input arrays containing strings. If their shapes differ, they must be broadcastable to a common shape.
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 where the comparison should be applied.
casting	str, optional	Defines the casting behavior when comparing the strings.
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 an array of boolean values where each element indicates whether the corresponding elements of x1 and x2 are equal. If both inputs are scalars, a single boolean value is returned.

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Examples

1. Comparing Two Identical Strings

Checking whether two string values are equal.

import numpy as np

# Define two string values
str1 = "apple"
str2 = "apple"

# Compare the two strings
result = np.strings.equal(str1, str2)

# Print the result
print("Are the strings equal?", result)

Output:

Are the strings equal? True

2. Comparing Two Arrays of Strings

Checking element-wise equality for two string arrays.

import numpy as np

# Define two arrays of strings
arr1 = np.array(["apple", "banana", "cherry"])
arr2 = np.array(["apple", "orange", "cherry"])

# Perform element-wise comparison
result = np.strings.equal(arr1, arr2)

# Print the result
print("Comparison result:", result)

Output:

Comparison result: [ True False  True]

3. Using Broadcasting to Compare a Single String with an Array

We compare a single string with each element of an array using broadcasting.

import numpy as np

# Define an array of strings
arr = np.array(["apple", "banana", "cherry"])

# Compare each element with a single string
result = np.strings.equal(arr, "banana")

# Print the result
print("Comparison with 'banana':", result)

Output:

Comparison with 'banana': [False  True False]

4. Using the out Parameter

Storing the comparison result in a predefined output array.

import numpy as np

# Define two arrays of strings
arr1 = np.array(["apple", "banana", "cherry"])
arr2 = np.array(["apple", "grape", "cherry"])

# Create an output array
output_array = np.empty_like(arr1, dtype=bool)

# Perform element-wise comparison and store result in output_array
np.strings.equal(arr1, arr2, out=output_array)

# Print the result
print("Comparison result:", output_array)

Output:

Comparison result: [ True False  True]

5. Using the where Parameter

Applying conditional element-wise comparison.

import numpy as np

# Define two arrays of strings
arr1 = np.array(["apple", "banana", "cherry"])
arr2 = np.array(["apple", "grape", "cherry"])

# Define a mask to specify where to perform comparison
mask = np.array([True, False, True])

# Compare strings only where mask is True
result = np.strings.equal(arr1, arr2, where=mask)

# Print the result
print("Comparison with mask:", result)

Output:

Comparison with mask: [ True False  True]

The comparison is performed only where mask=True, leaving the rest unchanged.