Python：将列表中字符串项目的索引号附加到该项目

Question

For any given list of string items, eg

my_list = ['foo', 'bar', 'baz', 'foo']

How does one append the index number of each item to it's corresponding item in the list? Forming a new list with the format, eg

new_list = ['foo0', 'bar1', 'baz2', 'foo3']

My example list only has four items, but I'm interested in a generalised answer for an arbitrary number of string items (something that works as well for a list of 4,000 string items as it does for 4)

Cheers!

Answer 1

A simpler way:

new_list = [elm + str(index) for index, elm in enumerate(my_list)]

UPDATE : With Python 3.6+ and formatted strings literals you can get a more readable code:

new_list = [f'{elm}{index}' for index, elm in enumerate(my_list)]

Answer 2

A straight for loop would work:

counter = 0
new_list = []
for each_item in the_list:
    new_list.append(each_item + str(counter))
    counter += 1

A list comprehension with enumerate() would also be fine, but less readable:

new_list = [each_item + str(index) for each_item, index in enumerate(the_list)]

Answer 3

try this.

EDIT: Explanation: The function below takes a list as an input and returns a list with the element numbers appended to the item. The number appended to the end of each item in the list is padded with zeros based on the length of the input list. So a list of length 30 with have appended numbers 00 through 29; a list of 3901 will have appended numbers 0000 through 3900.

from numpy import log10

def numberedList(inlist):
    i = 0
    z = int(log10(len(inlist))) + 1
    outlist = []
    for element in inlist:
        outlist.append(str(element) + str(i).zfill(z))
        i = i + 1
    return outlist

Answer 4

To create a list from a static list and a repeating list:

# need: ['A','B','C','First1','Middle1','Last1','First2','Middle2','Last2',...]
['A','B','C']+[s+str(n) for n in range(1,len(names)+1) for s in ['First','Middle','Last']]