Return a boolean array which is True where the string element in array starts with prefix in Python

To return a boolean array which is True where the string element in array starts with prefix, use the numpy.char.startswith() method in Python Numpy. The first parameter is the input array. The second parameter is the prefix.

Steps

At first, import the required libraries −

import numpy as np

Create a One-Dimensional array of strings −

arr = np.array(['KATIE', 'JOHN', 'KATE', 'KmY', 'BRAD'])

Displaying our array −

print("Array...\n",arr)

Get the datatype −

print("\nArray datatype...\n",arr.dtype)

Get the dimensions of the Array −

print("\nArray Dimensions...\n",arr.ndim)

Get the shape of the Array −

print("\nOur Array Shape...\n",arr.shape)

Get the number of elements of the Array −

print("\nNumber of elements in the Array...\n",arr.size)

To return a boolean array which is True where the string element in array starts with prefix, use the numpy.char.startswith() method −

print("\nResult (startswith)...\n",np.char.startswith(arr, 'K'))

Example

import numpy as np

# Create a One-Dimensional array of strings
arr = np.array(['KATIE', 'JOHN', 'KATE', 'KmY', 'BRAD'])

# Displaying our array
print("Array...\n",arr)

# Get the datatype
print("\nArray datatype...\n",arr.dtype)

# Get the dimensions of the Array
print("\nArray Dimensions...\n",arr.ndim)

# Get the shape of the Array
print("\nOur Array Shape...\n",arr.shape)

# Get the number of elements of the Array
print("\nNumber of elements in the Array...\n",arr.size)

# To return a boolean array which is True where the string element in array starts with prefix, use the numpy.char.startswith() method in Python Numpy
# The first parameter is the input array
# The second parameter is the prefix
print("\nResult (startswith)...\n",np.char.startswith(arr, 'K'))

Output

Array...
['KATIE' 'JOHN' 'KATE' 'KmY' 'BRAD']

Array datatype...
<U5

Array Dimensions...
1

Our Array Shape...
(5,)

Number of elements in the Array...
5

Result (startswith)...
[ True False True True False]