Repeat all the elements of a NumPy array of strings
Last Updated :
05 Mar, 2023
Let us see how to repeat all elements of the given array of string 3 times. Example :
Input : [‘Akash’, ‘Rohit’, ‘Ayush’, ‘Dhruv’, ‘Radhika’] Output : [‘AkashAkashAkash’, ‘RohitRohitRohit’, ‘AyushAyushAyush’, ‘DhruvDhruvDhruv’, ‘RadhikaRadhikaRadhika’]
We will be using the numpy.char.multiply(a, i) method for this task.
numpy.char.multiply(a, i)
Syntax : numpy.char.multiply(a, i) Parameters :
- a : array of str or unicode
- i : number of times to be repeated
Returns : Array of strings
Example 1 : Repeating 3 times.
Python3
import numpy as np
arr = np.array([ 'Akash' , 'Rohit' , 'Ayush' ,
'Dhruv' , 'Radhika' ], dtype = np. str )
print ("Original Array :")
print (arr)
new_array = np.char.multiply(arr, 3 )
print ("\nNew array :")
print (new_array)
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Output :
Original Array : [‘Akash’ ‘Rohit’ ‘Ayush’ ‘Dhruv’ ‘Radhika’] New array : [‘AkashAkashAkash’ ‘RohitRohitRohit’ ‘AyushAyushAyush’ ‘DhruvDhruvDhruv’ ‘RadhikaRadhikaRadhika’]
Time complexity: O(n), where n is the length of the input array
Auxiliary space: O(n).
Example 2: Repeating 2 times.
Python3
import numpy as np
arr = np.array([ 'Geeks' , 'for' , 'Geeks' ])
print ("Original Array :")
print (arr)
new_array = np.char.multiply(arr, 2 )
print ("\nNew array :")
print (new_array)
|
Output :
Original Array :
['Geeks' 'for' 'Geeks']
New array :
['GeeksGeeks' 'forfor' 'GeeksGeeks']
Time complexity: O(n), where n is the number of characters in the original array.
Auxiliary space: O(n), where n is the number of characters in the original array.
EXAMPLE 3 – Method 2: We can use a list comprehension to repeat each string in the array multiple times .
Python3
import numpy as np
arr = np.array([ 'Geeks' , 'for' , 'Geeks' ])
print ( "Original Array :" )
print (arr)
n = 2
new_array = np.array([s * n for s in arr])
print ( "\nNew array :" )
print (new_array)
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OUTPUT-
Original Array :
[‘Geeks’ ‘for’ ‘Geeks’]
New array :
[‘GeeksGeeks’ ‘forfor’ ‘GeeksGeeks’]
Time complexity: O(n * k), where n is the length of the input array and k is the number of times each string is repeated.
Auxiliary space: O(n), as we create a new list of length n to store the repeated strings. However, this is not counting the space needed for the input and output arrays.
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