Python – 避免最后出现的分隔符

给定一个整数列表，使用分隔符执行连接，避免末尾的额外分隔符。

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. 
 

方法#1：使用字符串切片

在此，我们使用字符串切片在形成后从字符串中切出最后一个字符。

Python3

# 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))

输出

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

方法 #2：使用 map() + join() + str()

在此，我们完全避免使用循环方法来解决这个问题，而使用map() 转换为字符串和join() 来执行连接任务。

Python3

# 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))

输出

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