Python – Avoid Last occurrence of delimitter

Given an Integer list, perform join with the delimiter, avoiding the extra delimiter at the end.

Input : test_list = [4, 7, 8, 3, 2, 1, 9], delim = “*” 
Output : 4*7*8*3*2*1*9 
Explanation : The rear “*” which usually occurs in concatenation, is avoided.

Input : test_list = [4, 7, 8, 3], delim = “*” 
Output : 4*7*8*3 
Explanation : The rear “*” which usually occurs in concatenation, is avoided. 
 

Method #1: Using String slicing

In this, we use string slice to slice off the last character from the string after forming.



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# Python3 code to demonstrate working of
# Avoid Last occurrence of delimitter
# Using map() + join() + str()
  
# initializing list
test_list = [4, 7, 8, 3, 2, 1, 9]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing delim
delim = "$"
  
# appending delim to join
# will leave stray "$" at end
res = ''
for ele in test_list:
    res += str(ele) + "$"
  
# removing last using slicing
res = res[:len(res) - 1]
  
# printing result
print("The joined string : " + str(res))

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Output

The original list is : [4, 7, 8, 3, 2, 1, 9]
The joined string : 4$7$8$3$2$1$9

Method #2 : Using map() + join() + str()

In this, we completely avoid loop method to solve this problem, and employ map() to convert to string and join() to perform task of join.

Python3

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# Python3 code to demonstrate working of
# Avoid Last occurrence of delimitter
# Using map() + join() + str()
  
# initializing list
test_list = [4, 7, 8, 3, 2, 1, 9]
  
# printing original list
print("The original list is : " + str(test_list))
  
# initializing delim
delim = "$"
  
# map extends string conversion logic
res = delim.join(map(str, test_list))
  
# printing result
print("The joined string : " + str(res))

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Output

The original list is : [4, 7, 8, 3, 2, 1, 9]
The joined string : 4$7$8$3$2$1$9

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