Building a FOR loop inside of a string that will be used to prompt the user for input

Question

I am having a hard time solving what I think SHOULD be an easy problem. I have a dictionary that consists of a key(interger that represents an option #) and a value (string that is a description of the option). I need to print each key value pair on a separate line inside of the input function.

file_codes = {2: 'iosFile',
              3: 'startup',
              4: 'running'}
host_ip = '10.10.10.10'
users_numeric_entry = int(input(f'Please pick a configuration to copy for: {host_ip}\n))

Input prompt should be like below:

Please pick a configuration to copy for: 10.10.10.10

2 - iosFile
3 - startup
4 - running
:

I feel that I need a to create a for loop to iterate through the dictionary, but I am having a hard time coming up with the code to achieve my desired output.

dictionaries are not a sorted structure so you might consider moving to a list and `enumerate` it. (considering the options are sequential...) — Tomerikoo, Jul 17 '19 at 15:40
I would second @Tomerikoo 's point. The answer I gave below will match the correct #s to prompts, but there is no guarantee of order — Zachary Oldham, Jul 17 '19 at 15:50
@Tomerikoo because it is worth noting and I wanted to mention that my answer below has not guarantee of order? — Zachary Oldham, Jul 17 '19 at 15:56
@Tomerikoo dictionaries have been ordered since 3.6 (an implementation detail) and 3.7 (guaranteed) — roganjosh, Jul 17 '19 at 15:57
@roganjosh I looked it up and added notes on that in my answer below — Zachary Oldham, Jul 17 '19 at 15:59
@Tomerikoo yeah, that is what 'I second that' typically means — Zachary Oldham, Jul 17 '19 at 16:01
@Tomerikoo lol no problem, yeah it's an english idiom, meaning you agree — Zachary Oldham, Jul 17 '19 at 16:02
@roganjosh you forgot to mention an important deatil, they are [**insertion** ordered](https://stackoverflow.com/a/39980744/6045800) — Tomerikoo, Jul 17 '19 at 16:16

Zachary Oldham · Accepted Answer · 2019-07-17T16:50:21.377

2

I would print things out first, and then prompt with just :

print(f'Please pick a configuration to copy for: {host_ip}\n')
for k, v in file_codes.items():
    print(str(k) + ' - ' + v)
users_numeric_entry = int(input(':'))

If you are using python 2.x then dictionaries are not ordered and there is no guarantee it will print in the order you expect. In python 3.6+ they are ordered.

edited Jul 17 '19 at 16:50

answered Jul 17 '19 at 15:39

Zachary Oldham

838
1
5
21

score 2 · Answer 2 · answered Jul 17 '19 at 15:45

Something like this:

file_codes = {2: 'iosFile',
              3: 'startup',
              4: 'running'}
host_ip = '10.10.10.10'
menu = '\n'.join(['{} - {}'.format(k, v) for k, v in file_codes.items()])
users_numeric_entry = int(input(f'Please pick a configuration to copy for: {host_ip}\n {menu}'))

score 2 · Answer 3 · answered Jul 17 '19 at 15:46

2

I'm a huge advocate of the string formatting in Python. I would recommend looking into the abilities of the ''.format() options.

for k, v in sorted(file_codes.items()):
      print('{} - {}'.format(k, v))

answered Jul 17 '19 at 15:46

pmackni

307
3
12

Personally, I prefer the list comprehension of balderman's solution to mine, but any of these should do the trick. I prefer the ''.format method for some of the added options in formatting the string beyond just printing a variable. – pmackni Jul 17 '19 at 15:51
most (if not all) functionalities of `format` exist in `f-strings` – Tomerikoo Jul 17 '19 at 15:57
1

It's just most, not all. I looked into it extensively a while ago for a script I was working on and found better controls existed in the `format` options that don't have an `f-strings` equivalent. For general use, those extra controls could be considered niche and most formatting can be accomplished with either. I tend to have more niche needs when I script, so I typically prefer `format`. – pmackni Jul 17 '19 at 16:23
1

I'd like to alter my previous viewpoint a little. `f-strings` do offer a few added controls that over `format` as well as a performance boost, so `f-strings` are slightly better in general, though it's probably more a question of preference unless you're covering such a large amount of text that it actually creates a performance impact. – pmackni Jul 17 '19 at 16:43
1

Agree with what you say. I personnally am too still stuck with `format` as I believe will take me time to get used-to `f-s` and also lazy to change in all my project :) Just pointed out in my comment for future reference for readers – Tomerikoo Jul 17 '19 at 16:48
I missed this point when I previously looked into them, but their ability to contain any valid python is pretty nice if for some reason you need to call a method in the middle of a string. Maybe one day we'll catch up. :) – pmackni Jul 17 '19 at 16:51

score -2 · Answer 4 · answered Jul 17 '19 at 15:38

In [34]: file_codes = {2: 'iosFile', 
    ...:               3: 'startup', 
    ...:               4: 'running'}                                                                                                                                                                                                                                                                                          

In [35]: for k,v in sorted(file_codes.items(), key=operator.itemgetter(0)): print(k, '-', v)                                                                                                                                                                                                                                  
2 - iosFile
3 - startup
4 - running

Building a FOR loop inside of a string that will be used to prompt the user for input

4 Answers4