How to remove tuples in a list of tuples when the value of the first tuple in contained in an other list?

Question

I have a list containing tuples and I would like to remove tuples that contain words in the first position of the tuple based on words from a second list.

list_of_tuples = [
("apple",2),
("banana",54), 
("flower", 5), 
("apple",4), 
("fruit", 3)
]

list_of_words = [
"apple", 
"banana"
]

The final result should look like this:

 [("flower", 5), ("fruit", 3)]

Asked By: Elisa Nu

||

Source

Answer 1

This code will do the trick:

list_of_tuples = [
    ("apple", 2),
    ("banana", 54),
    ("flower", 5),
    ("apple", 4),
    ("fruit", 3)
]

list_of_words = [
    "apple",
    "banana"
]

final_list_of_tuples = [tup for tup in list_of_tuples if tup[0] not in list_of_words]

print(final_list_of_tuples)

The one liner technique is called a list comprehension.
You can find more information about it here:

Python List Comprehensions

Answered By: Nimrod Shanny

Answer 2

Rather than a complete solution, here is a breakdown of the various operations you can put together to accomplish your task. Hopefully it gives you a feel for the Python building blocks you can use for these types of problems in the future:

list_of_tuples = [
    ("apple",2),
    ("banana",54), 
    ("flower", 5), 
    ("apple",4), 
    ("fruit", 3)
]

list_of_words = ["apple", "banana"]

# demonstrates tuple unpacking in Python
word, quantity = list_of_tuples[0]
print(word, quantity)

# demonstrates how to test against a collection
print(word in list_of_words)

# demonstrates how to iterate over a list of tuples and unpack
for word, quantity in list_of_tuples:
    print(f"word: {fruit}, quantity: {quantity}")

# demonstrates how to create a new list from an existing list
new_list_of_tuples = []
for word, quantity in list_of_tuples:
    if word != "flower":
        new_list_of_tuples.append((word, quantity))
print(new_list_of_tuples)

Output:

apple 2
True
word: apple, quantity: 2
word: apple, quantity: 54
word: apple, quantity: 5
word: apple, quantity: 4
word: apple, quantity: 3
[('apple', 2), ('banana', 54), ('apple', 4), ('fruit', 3)]

Answered By: rhurwitz

How to remove tuples in a list of tuples when the value of the first tuple in contained in an other list?

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