Python – Filter index similar values
Sometimes, while working with Python dictionaries, we can have a problem in which we need to extract all the values in values lists that match the filtered indices from matching values from list with some key in dictionary. This kind of application can occur in web development.
Input : test_dict = {“Gfg” : [4, 5, 7], “is” : [5, 6, 8], “best” : [10, 7, 4]} Output : {“Gfg” : [4, 5, 7], “is” : [5, 6, 8], “best” : [10, 7, 4]} Input : test_dict = {“Gfg” : [4, 20, 5, 7], “is” : [5, 17, 6, 8], “best” : [10, 11, 7, 4]} Output : {‘Gfg’: [4, 5, 7], ‘is’: [5, 6, 8], ‘best’: [10, 7, 4]}
Method #1 : Using loop + zip() + defaultdict() The combination of above methods can be used to solve this problem. In this, we initialize the defaultdict with list, bind all the keys with zip() and use loop to append the required elements.
Python3
from collections import defaultdict
test_dict = {"Gfg" : [ 1 , 4 , 5 , 6 , 7 ], " is " : [ 5 , 6 , 8 , 9 , 10 ],
"best" : [ 10 , 7 , 4 , 11 , 23 ]}
print ("The original dictionary : " + str (test_dict))
filt_list = [ 4 , 5 , 7 ]
res = defaultdict( list )
for x, y, z in zip (test_dict[ 'Gfg' ], test_dict[ 'is' ], test_dict[ 'best' ]):
if x in filt_list:
res[ 'Gfg' ].append(x)
res[ 'is' ].append(y)
res[ 'best' ].append(z)
print ("The filtered dictionary : " + str ( dict (res)))
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Output :
The original dictionary : {‘Gfg’: [1, 4, 5, 6, 7], ‘is’: [5, 6, 8, 9, 10], ‘best’: [10, 7, 4, 11, 23]} The filtered dictionary : {‘Gfg’: [4, 5, 7], ‘is’: [6, 8, 10], ‘best’: [7, 4, 23]}
Method #2 : Using list comprehension + dictionary comprehension The combination of above functionalities can be used to solve this problem. In this, we extract indices using list comprehension and filtering from other keys is done using dictionary comprehension.
Python3
test_dict = {"Gfg" : [ 1 , 4 , 5 , 6 , 7 ], " is " : [ 5 , 6 , 8 , 9 , 10 ],
"best" : [ 10 , 7 , 4 , 11 , 23 ]}
print ("The original dictionary : " + str (test_dict))
filt_list = [ 4 , 5 , 7 ]
temp = [test_dict[ 'Gfg' ].index(idx) for idx in filt_list]
res = {key : [test_dict[key][idx] for idx in temp] for key in test_dict.keys()}
print ("The filtered dictionary : " + str (res))
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Output :
The original dictionary : {‘Gfg’: [1, 4, 5, 6, 7], ‘is’: [5, 6, 8, 9, 10], ‘best’: [10, 7, 4, 11, 23]} The filtered dictionary : {‘Gfg’: [4, 5, 7], ‘is’: [6, 8, 10], ‘best’: [7, 4, 23]}
Using a set to store the unique values:
Approach:
Create an empty set to store unique values.
Iterate through the values in the dictionary.
Convert each value to a tuple to make it hashable.
Check if the tuple is already in the set of unique values.
If the tuple is already in the set, remove the current key-value pair from the dictionary.
If the tuple is not in the set, add it to the set of unique values.
Return the filtered dictionary.
Python3
def filter_dict(test_dict):
unique_values = set ()
for value in test_dict.values():
unique_value = tuple (value)
if unique_value in unique_values:
del test_dict[key]
else :
unique_values.add(unique_value)
return test_dict
test_dict = { "Gfg" : [ 4 , 5 , 7 ], "is" : [ 5 , 6 , 8 ], "best" : [ 10 , 7 , 4 ]}
print (filter_dict(test_dict))
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Output
{'Gfg': [4, 5, 7], 'is': [5, 6, 8], 'best': [10, 7, 4]}
Time complexity: O(n)
Auxiliary Space: O(n)
Last Updated :
11 Apr, 2023
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