Python – Vertical Grouping Value Lists

Sometimes, while working with Python dictionaries, we can have a problem in which we need to group all the list values vertically, i.e w.r.t similar index. This kind of problem can have applications in many domains such as web development. Let’s discuss certain ways in which this problem can be solved.

Input : test_dict = {‘Gfg’: [4, 8], ‘is’: [87, 2], ‘best’ : [14, 1]}
Output : [(4, 87, 14), (8, 2, 1)]

Input : test_dict = {‘Gfg’: [4, 6, 7, 8]}
Output : [(4, ), (6, ), (7, ), (8, )]

Method #1 : Using list comprehension + zip() + * operator
The combination of above functions can be used to solve this problem. In this, we perform the task of extracting values using values() and zip() is used to perform vertical grouping after unpacking using * operator.

# Python3 code to demonstrate working of
# Vertical Grouping Value Lists
# Using list comprehension + zip() + * operator

# initializing dictionary
test_dict = {'Gfg': [4, 5, 7], 'is': [8, 9, 10], 'best' : [10, 12, 14]}

# printing original dictionary
print("The original dictionary is : " + str(test_dict))

# Vertical Grouping Value Lists
# Using list comprehension + zip() + * operator
res = [tuple(idx) for idx in zip(*test_dict.values())]

# printing result
print("The grouped values : " + str(res))

Output :

The original dictionary is : {'Gfg': [4, 5, 7], 'is': [8, 9, 10], 'best': [10, 12, 14]}
The grouped values : [(4, 8, 10), (5, 9, 12), (7, 10, 14)]

Method #2 : Using list() + zip() + values()
The combination of above functions can be used to solve this problem. In this, we perform the task similar to above method, the difference being using list() instead of list comprehension.

# Python3 code to demonstrate working of
# Vertical Grouping Value Lists
# Using list() + zip() + values()

# initializing dictionary
test_dict = {'Gfg': [4, 5, 7], 'is': [8, 9, 10], 'best' : [10, 12, 14]}

# printing original dictionary
print("The original dictionary is : " + str(test_dict))

# Vertical Grouping Value Lists
# Using list() + zip() + values()
res = list(zip(*test_dict.values()))

# printing result
print("The grouped values : " + str(res))

Output :

The original dictionary is : {'Gfg': [4, 5, 7], 'is': [8, 9, 10], 'best': [10, 12, 14]}
The grouped values : [(4, 8, 10), (5, 9, 12), (7, 10, 14)]