Find the length of each string element in the Numpy array

Last Updated : 06 Mar, 2019

NumPy builds on (and is a successor to) the successful Numeric array object. Its goal is to create the corner-stone for a useful environment for scientific computing. NumPy provides two fundamental objects: an N-dimensional array object (ndarray) and a universal function object (ufunc).

In this post we are going to discuss ways in which we can find the length of each string element in the given numpy array.

Problem #1 : Given a numpy array whose underlying data is of string type. Find the length of each element in the given object.

Solution : We are going to use numpy.vectorize() function to find the length of each element in the given numpy array object.

# importing the numpy library as np
import numpy as np
  
# Create a numpy array
arr = np.array(['New York', 'Lisbon', 'Beijing', 'Quebec'])
  
# Print the array
print(arr)

Output :

Now we will use numpy.vectorize() function to find the length of each element in the given numpy array object.

# Use vectorize function of numpy
length_checker = np.vectorize(len)
  
# Find the length of each element
arr_len = length_checker(arr)
  
# Print the length of each element
print(arr_len)

Output :

As we can see in the output, we have successfully calculated the length of each string element in the given numpy array object.

Problem #2 : Given a numpy array whose underlying data is of string type. Find the length of each element in the given object.

Solution : We are going to use List comprehension technique to find the length of each element in the given numpy array object.

# importing the numpy library as np
import numpy as np
  
# Create a numpy array
arr = np.array(['New York', 'Lisbon', 'Beijing', 'Quebec'])
  
# Print the array
print(arr)

Output :

Now we will use List comprehension technique to find the length of each element in the given numpy array object.

# Find the length of each element
arr_len = [len(i) for i in arr]
  
# Print the length of each element
print(arr_len)

Output :

As we can see in the output, we have successfully calculated the length of each string element in the given numpy array object.

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Find the length of each string element in the Numpy array