Creating python dictionaries using for loop

Question

I make a bunch of matrices that I want to store in python dictionaries and I always find myself typing the same thing for every state that I want to build, i.e.

Ne21_1st_state = {}
Ne21_2nd_state = {}
Ne21_3rd_state = {}
Ne21_4th_state = {}
Ne21_5th_state = {}
Ne21_6th_state = {}
...
Ne21_29th_state = {}
Ne21_30th_state = {}

Can somebody help me automate this using python for loops?
Thanks in advance!

I want something like this:

for i in range(3, 11):
    states = f'Ar36_{i}th_state'
    print(states)

where the output would be:

Ar36_3th_state
Ar36_4th_state
Ar36_5th_state
Ar36_6th_state
Ar36_7th_state
Ar36_8th_state
Ar36_9th_state
Ar36_10th_state

but instead of printing it it would create individual dictionaries named Ar36_3th_state, Ar36_4th_state, Ar36_5th_state, ...

https://stackoverflow.com/questions/1373164/how-do-i-create-variable-variables — Ture Pålsson, Jan 14 '22 at 05:00

score 1 · Answer 1 · answered Jan 14 '22 at 05:34

1

can't we make a List of dictionaries

List of 30 (or any N) elements where each element is a dictionary with key = "Ar36_{i}th_state" and value = {whatever value you want}

answered Jan 14 '22 at 05:34

Rajarshi Ghosh

452
1
9

Yes that's what I want to accomplish. Only if I know how to code it up... – vlaaaaaddd Jan 14 '22 at 05:39
Taking by your example - `lst = [] for i in range(3, 11): state = 'Ar36_' + str(i) + 'th_state' lst.append({'key' : state, 'value': i})` – Rajarshi Ghosh Jan 14 '22 at 05:54

score 0 · Answer 2 · answered Jan 14 '22 at 05:06

One way I've done this is using list comprehension.

key = list(
str(input(f"Please enter a Key for value {x + 1}: "))
if x == 0
else str(input(f"\nPlease enter a Key for value {x + 1}: "))
for x in range(3))

value = list(str(input(f"\nPlease enter a Bool for value {x + 1}: ")) 
for x in range(3))

BoolValues = dict(zip(key, value))

I first create a list of keys followed by a list of the values to be stored in the keys. Then I just zip them together into a dictionary. The conditional statements in the first list are only for a slightly better user-experience with \n being added if it's passed the first input.

Actually now that I look back on the question it may be slightly different to what I was thinking, are you trying to create new dictionaries for every matrix? If that is the case, is it something similar to this?: How do you create different variable names while in a loop?

Yes. I want to create each dictionary (`Ne21_1st_state`, `Ne21_2nd_state`, `Ne21_3rd_state`,...) using a couple of lines of code without having to manually type each one from `1st` all the way to `30th` state. — vlaaaaaddd, Jan 14 '22 at 05:11

Marcel Suleiman · Accepted Answer · 2022-01-14T05:45:53.677

0

You can create "name" of pseudo variable and use it as key in dictionary like:

my_dic = {1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'e'}
my_empty_dic = {}

solution = {}

for i in range(1, 31):
    name = 'Ne21_'+str(i)+'st_state'

    #solution[name] = my_dic
    solution[name] = my_empty_dic

for pseudo_variable in solution:
    print(pseudo_variable, solution[pseudo_variable])

print(solution['Ne21_16st_state'])

for pseudo_variable in solution:
    if '_16st' in pseudo_variable:
        print(pseudo_variable, solution[pseudo_variable])

edited Jan 14 '22 at 05:45

answered Jan 14 '22 at 05:31

Marcel Suleiman

106
4

this is close but ultimately I want to create those (empty) dictionaries (named `Ne21_1st_state`, `Ne21_2nd_state`, ...) at the end so I can attach some values to them – vlaaaaaddd Jan 14 '22 at 05:41
just replace my_dic by empty_dic... – Marcel Suleiman Jan 14 '22 at 05:46
I tried that but it's just printing the names of the dictionaries (not creating them) – vlaaaaaddd Jan 14 '22 at 05:49
add this line at the end "print(solution)" and run it. What you see? 1 big dictionary, fully of 30 empty dictionaries with names 1st, 2st etc. – Marcel Suleiman Jan 14 '22 at 05:54
True.. but I think I might have been unclear on what I really want to achieve here. Basically, I'd like a code that gives me an action equivalent to typing in `Ne21_1st_state = {}`, `Ne21_2nd_state = {}`, `Ne21_3rd_state = {}`, ... all the way to however many state I have where each one creates an empty dictionary. – vlaaaaaddd Jan 14 '22 at 06:07
you want Ne21_1st_state = {} ... now you have solution['Ne21_1st_state'] = {}. Your dynamic created variable is -> solution['Ne21_1st_state'] <- . If you want add something to "Ne21_1st_state" just use solution['Ne21_1st_state'] = 'value'. In this case, key in dictionary is something like variable. – Marcel Suleiman Jan 14 '22 at 06:20
oh shooot! I see what you're saying. It's not exactly what I was looking for but I can tweak a few things to get it to my liking. Thank you!! – vlaaaaaddd Jan 14 '22 at 06:23

Creating python dictionaries using for loop

3 Answers3