CODEWITHSUNDEEP
pythondictionary
Norfeldt
Norfeldt

Reputation: 9718

Python dict: get values sorted by a list of keys

I don't wan to use numpy to work with a 2D matrix

I figured out how to create something that looks like a row and column dictionary. It works fine if I want to look up single values.

But I'm having trouble figuring out how to get values from a row in the same order as I use my columns

from collections import defaultdict

dic = defaultdict(dict)
rowKeys = ['1','2','3']
columnKeys = ['alfa', 'omega', 'bravo', 'charlie']

# Filling up the dictionary with values
from random import randrange
for rKey in rowKeys:
    for cKey in columnKeys:
        dic[rKey][cKey] = randrange(50)

""" 
    print dic
    defaultdict(<type 'dict'>, {
    '1': {'omega': 28, 'charlie': 42, 'alfa': 13, 'bravo': 45}, 
    '3': {'omega': 8, 'charlie': 5, 'alfa': 13, 'bravo': 4}, 
    '2': {'omega': 19, 'charlie': 42, 'alfa': 29, 'bravo': 26}})
"""
# print dic[rowKeys[0]].keys()
# ['omega', 'charlie', 'alfa', 'bravo']

# In [28]: print dic[rowKeys[0]].values()
# [28, 42, 13, 45]

I want a list of values in the "original" order

[13, 28, 45, 42]

Is there a clean easy-to-read way of doing this?

UPDATE

@jamylak came with an answer that solved my specific problem.

But it did not truly answer my question of how to get values by a list. Suppose I change the order of columnKeys alphabetically (or by other non-logic order) and want to get at list of values returned in that order. How would I go about that __?

Upvotes: 0

Views: 2468

Answers (4)

Mark Seagoe
Mark Seagoe

Reputation: 589

myDict = {'k42':'cat', 'k5':'fish', 'k1':'bird', 'k9':'dog'}
keyList = ['k1', 'k42', 'k9', 'k5']
outList = [myDict[x] for x in keyList]

Upvotes: 0

thkang
thkang

Reputation: 11543

clean and easy-to-read way would be using list comprehensions.

def readdict(D, rowkeys=(1, 2, 3)):

    def readcol(d, columnKeys=('alfa', 'omega', 'bravo', 'charlie')):
        return [d[key] for key in columnKeys]

    return [readcol(D[key]) for key in rowkeys]


'''outputs :

[[13, 28, 45, 42], 
 [29, 19, 26, 42], 
 [13,  8,  4,  5]]'''

Upvotes: 3

HennyH
HennyH

Reputation: 7944

for row in dic.values(): #get each row 'dict'
    for k,v in sorted(row.items(),key=lambda k: columnKeys.index(k[0])): #sort base on index of key occurring in columnKeys
        print(k,v)

Would output for example:

('alfa', 43)
('omega', 30)
('bravo', 24)
('charlie', 2)

For {'omega': 29, 'charlie': 11, 'alfa': 4, 'bravo': 3}

Upvotes: 1

jamylak
jamylak

Reputation: 133764

from collections import defaultdict, OrderedDict

dic = defaultdict(OrderedDict)
rowKeys = ['1','2','3']
columnKeys = ['alfa', 'omega', 'bravo', 'charlie']

# Filling up the dictionary with values
from random import randrange

for rKey in rowKeys:
    for cKey in columnKeys:
        dic[rKey][cKey] = randrange(50)

Upvotes: 7

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