How to append a integer iteration into a string in python?

Question

So this is my problem:

first I iterate

for i in range(1,21):
    print (i)

then I have a variable basename="Station"

I want a result where the output is Station_1.txt, Station_2.txt etc.

I managed to add the "_" to the variable basename like

mylist1 = ("_")
s = (basename)
for item in mylist1:
    s += item

but now I have the problem on how to get the iteration on top of the variable basename, I could get is as it own like "Station_, 1, Station_, 2" but not inside the string itself.

Sorry, a total beginner here :)

score 9 · Answer 1 · answered Sep 25 '18 at 14:09

You can do this in one line! Try the following:

basename = "Station"
result = ["{}_{}.txt".format(basename, i) for i in range(1, 21)]
print(result)`

 >> ['Station_1.txt','Station_2.txt','Station_3.txt', 
     'Station_4.txt','Station_5.txt','Station_6.txt', 
     'Station_7.txt','Station_8.txt','Station_9.txt', 
     'Station_10.txt','Station_11.txt',Station_12.txt',
     'Station_13.txt','Station_14.txt','Station_15.txt',
     'Station_16.txt','Station_17.txt','Station_18.txt',
     'Station_19.txt','Station_20.txt']`

score 3 · Accepted Answer · answered Sep 25 '18 at 13:59

Do you want something like this?

basename = "Station"
for i in range(1, 21):
    value = basename + "_" + str(i) + ".txt"
    print(value)

output:

Station_1.txt
Station_2.txt
Station_3.txt
Station_4.txt
Station_5.txt
Station_6.txt
Station_7.txt
Station_8.txt
Station_9.txt
Station_10.txt
Station_11.txt
Station_12.txt
Station_13.txt
Station_14.txt
Station_15.txt
Station_16.txt
Station_17.txt
Station_18.txt
Station_19.txt
Station_20.txt

score 2 · Answer 3 · answered Sep 25 '18 at 14:01

2

I would use .format(). See https://docs.python.org/3.3/library/stdtypes.html#str.format

For example:

base_string = 'Station'
for i in range(1,21):
    print('{}_{}.txt'.format(base_string, i))

answered Sep 25 '18 at 14:01

k0nG

4,716
2
20
18

In python 3.6+ you can also use `f` string `print(f"{base_string}_{i}')` . Docs: https://docs.python.org/3/reference/lexical_analysis.html#f-strings – k0nG Nov 13 '18 at 12:33

score 1 · Answer 4 · answered Sep 25 '18 at 14:03

You can use string formatting to forget about worrying about integers

You still loop over with the number as your parameter and keep the base name the same:

base = 'Station'
for i in range(1, 21):
    name = '{}_{}.txt'.format(base, i)
    print(name)  # or do whatever with 'name'

Martin Evans · Answer 5 · 2018-09-25T16:52:06.870

String concatenation is best avoided if possible. An alternative is Python now supports format strings by prefixing f which could be used to solve your problem as follows:

base_string = 'Station'

for i in range(1, 21):
    print(f'{base_string}_{i}.txt')

This was added in Python 3.6. It could also be useful to zero pad your strings which would ensure the strings are sorted correctly:

base_string = 'Station'

for i in range(1, 21):
    print(f'{base_string}_{i:02}.txt')

This would give you:

Station_01.txt
Station_02.txt
Station_03.txt
Station_04.txt
Station_05.txt
Station_06.txt
Station_07.txt
Station_08.txt
Station_09.txt
Station_10.txt
Station_11.txt
Station_12.txt
Station_13.txt
Station_14.txt
Station_15.txt
Station_16.txt
Station_17.txt
Station_18.txt
Station_19.txt
Station_20.txt

How to append a integer iteration into a string in python?

5 Answers5