How to form a dictionary with different parameters?

Question

I have a class Test with class parameter

parameters = {'first': [1,2,3,4], 'second': [5,6,7]}. I want to convert it into a dictionary so that it will be "{'Test': 'first':1 'second':5}"

what I tried is: di = {} di = dict(itertools.izip(name, vals))

where I'm getting Test i.e classnane in variable name i.e name = Test and

vals = {'first': [1,2,3,4], 'second': [5,6,7]} Though I want it as "{'Test': 'first':1 'second':5}", shouldn't this print "{'Test': 'first':[1,2,3,4] 'second':[5,6,7]}"?? Instead what I'm getting when I'm printing di is {'Test': 'first'}. I'm not getting where my logic is going wrong.

score 4 · Answer 1 · answered Aug 18 '14 at 21:46

4

Use a dictionary comprehension:

subjects = ['Physics', 'Chemistry', 'Maths']
{subject: {} for subject in subjects}

answered Aug 18 '14 at 21:46

mgilson

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jh314 · Answer 2 · 2014-08-18T21:58:05.990

2

If you are working with Python 2, you can use dict() constructor:

subjects =  ['Physics', 'Chemistry', 'Maths']
dict(((subject, {}) for subject  in subjects))

If you are using Python 3, you can use dictionary comprehension:

subjects =  ['Physics', 'Chemistry', 'Maths']
{subject: {} for subject in subjects}

edited Aug 18 '14 at 21:58

answered Aug 18 '14 at 21:46

jh314

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This one gives TypeError: unhashable type: 'list' – NikAsawadekar Aug 18 '14 at 21:54
Are you using Python 2 or 3? – jh314 Aug 18 '14 at 21:56
2.7.7. I tried it with {subject: {} for subject in subjects} even with dict(((subject, {}) for subject in subjects)) still same error. – NikAsawadekar Aug 18 '14 at 22:00
It should work. I think the error is referring to something else. Maybe you have nested lists in your subjects list? – jh314 Aug 18 '14 at 22:07
Nope, it's not nested list. – NikAsawadekar Aug 18 '14 at 22:56

score 1 · Answer 3 · 2014-08-18T21:50:46.247

1

Try using dict comprehension:

Input:

{x: {} for x in ['Physics', 'Chemistry', 'Maths']}

Output:

{'Maths': {}, 'Chemistry': {}, 'Physics': {}}

edited Aug 18 '14 at 21:50

answered Aug 18 '14 at 21:48

It looks like OP wants the items to be empty dicts -- If OP really wants an empty string, then `dict.fromkeys` is a great option. c.f. http://stackoverflow.com/q/14507591/748858 – mgilson Aug 18 '14 at 21:49
right, i realized that fact. dict comprehension is the solution to the question @mgilson – Aug 18 '14 at 21:51

score 0 · Answer 4 · answered Aug 18 '14 at 21:47

0

That is a basic for loop. Itertools is way to complex for this kind of stuff.

>>> l = ['Physics', 'Chemistry', 'Maths']
>>> d = {}
>>> for i in l:
    d[i] ={}


>>> d
{'Chemistry': {}, 'Physics': {}, 'Maths': {}}

answered Aug 18 '14 at 21:47

Hey I tried it and got working but I have one question why it's in different order? Instead of {'Physics': {}, 'Chemistry': {}, 'Maths': {}} why we have - {'Chemistry': {}, 'Physics': {}, 'Maths': {}} ?? What I need to do to get it in right order? – NikAsawadekar Aug 19 '14 at 14:36
In python a dict is not sorted. If you really need to go through the dict sorted, just use `for key in sorted(d):`. P.S. this is just a simple for loop, the other answers are more efficient, faster and generally better. – Aug 19 '14 at 14:45

How to form a dictionary with different parameters?

4 Answers4