Problem Formulation
💬 Challenge: Given an integer n. How to create a list of n empty strings '' in Python?
Here are three examples:
- Given
n=0. Create list[]. - Given
n=3. Create list['', '', '']. - Given
n=5. Create list['', '', '', '', ''].
Method 1: List Multiplication
You can create a list of n empty strings using the list concatenation (multiplication) operator on a list with one empty string using the expression [''] * n. This replicates the same identical empty string object to which all list elements refer. But as strings are immutable, this cannot cause any problems through aliasing.
def create_list_empty_strings(n):
return [''] * n
print(create_list_empty_strings(0))
# []
print(create_list_empty_strings(3))
# ['', '', '']
print(create_list_empty_strings(5))
# ['', '', '', '', '']Method 2: List Comprehension
You can create a list of n empty strings by using list comprehension statement ['' for _ in range(n)] that uses the range() function to repeat the creation and addition of an empty string n times.
def create_list_empty_strings(n):
return ['' for _ in range(n)]
print(create_list_empty_strings(0))
# []
print(create_list_empty_strings(3))
# ['', '', '']
print(create_list_empty_strings(5))
# ['', '', '', '', '']
Method 3: For Loop and append()
To create a list of n empty strings without special Python features, you can also create an empty list and use a simple for loop to add one empty string at a time using the list.append() method.
def create_list_empty_strings(n):
my_list = []
for i in range(n):
my_list.append('')
return my_list
print(create_list_empty_strings(0))
# []
print(create_list_empty_strings(3))
# ['', '', '']
print(create_list_empty_strings(5))
# ['', '', '', '', '']
Summary
There are three best ways to create a list with n empty strings.
- List concatenation
[''] * n - List comprehension
['' for _ in range(n)] - Simple
forloop with listappend('')on an initially empty list
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Programmer Humor
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