Python | Construct string from character frequency tuple

Sometimes, while working with data, we can have a problem in which we need to perform construction of string in a way that we have a list of tuple having character and it’s corresponding frequency and we require to construct a new string from that. Let’s discuss certain ways in which this task can be performed.

Method #1 : Using loop
This is brute force method in which this task can be performed. In this, we iterate the list and perform string concatenation using * operator and keep building string this way.

# Python3 code to demonstrate working of 
# String construction from character frequency 
# using loop 
  
# initialize list  
test_list = [('g', 4), ('f', 3), ('g', 2)] 
  
# printing original list  
print("The original list : " + str(test_list)) 
  
# String construction from character frequency 
# using loop 
res = '' 
for char, freq in test_list: 
    res = res + char * freq 
  
# printing result 
print("The constructed string is : " + str(res)) 

Output :

The original list : [('g', 4), ('f', 3), ('g', 2)]
The constructed string is : ggggfffgg

Method #2 : Using join() + list comprehension
The combination of above functionalities can be used to perform this task. In this, we perform the task of extraction using list comprehension and making string using join().

# Python3 code to demonstrate working of 
# String construction from character frequency 
# using join() + list comprehension 
  
# initialize list  
test_list = [('g', 4), ('f', 3), ('g', 2)] 
  
# printing original list  
print("The original list : " + str(test_list)) 
  
# String construction from character frequency 
# using join() + list comprehension 
res = ''.join(char * freq for char, freq in test_list) 
  
# printing result 
print("The constructed string is : " + str(res)) 

Output :

The original list : [('g', 4), ('f', 3), ('g', 2)]
The constructed string is : ggggfffgg

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