Lists to Dict need return method

Question

I am trying to return a dictionary with key/value pairs, but this is what I got and it does not work.

def lists_to_dict(keys, value):
    for i in values:
        value[i]=map(int, value[i])
        return keys

Welcome to stack overflow! Your question is unclear. What is your input to the function, what is the current output, and what is the expected output? Please [edit] this to make a [mcve] — G. Anderson, Oct 29 '20 at 18:11

Kroshka Kartoshka · Accepted Answer · 2020-10-29T18:18:20.723

2

Try this (best option):

return dict(zip(keys, value))

or this (a bit overly verbose):

return {key: v for key, v in zip(keys, value)}

or this (to show that one just arrived to Python from C++):

return {keys[i]: value[i] for i in range(len(keys))}

For {key: ...} construction you can google dict comprehensions.

For zip you can google zip.

These are important things so they might be worth reading, hence the links.

edited Oct 29 '20 at 18:18

answered Oct 29 '20 at 18:14

Kroshka Kartoshka

1,035
5
23

To be clear, #3 is extremely non-idiomatic (and slower, and more prone to errors with mismatched input sizes). Basically any case of `for i in range(len(someseq)):` which does `someseq[i]` is a problem; indexing another sequence with it makes it worse. #2 is more customizable, but not necessary unless you're filtering or mutating the keys or values. – ShadowRanger Oct 29 '20 at 18:17
Yes, added this characteristic to the answer, thanks – Kroshka Kartoshka Oct 29 '20 at 18:18

score 0 · Answer 2 · answered Oct 29 '20 at 18:18

0

If you are trying to convert a two list into a dict, try using the zip command.

my version

def list_to_dict(keys, value):
return dict(zip(keys, value))

list_to_dict(['A', 'B', 'C'], [10, 20, 30])

Result

{'A': 1, 'B': 2, 'C': 3}

answered Oct 29 '20 at 18:18

Fjord

31
3

score 0 · Answer 3 · answered Oct 29 '20 at 18:18

You make a for loop for "valueS", yet you give the function "value" First you should initialise the dictionary, try:

def lists_to_dict(keys, values): 
    out_dictionary = {}
    for idx, key in enumerate(keys):  ## idx will be an integer as index of keys
        out_dictionary[key] = values[idx] ## assumes values and keys is equal length
    return out_dictionary

Lists to Dict need return method

3 Answers3