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@IvanFrecia
Created May 3, 2021 18:30
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Data Collection and Processing with Python - Week 2 - 23.3 - Filter
# Now consider another common pattern: going through a list and keeping only those items that meet certain criteria. This is called a filter.
# Again, this pattern of computation is so common that Python offers a more compact and general way to do it,
# the filter function. filter takes two arguments, a function and a sequence. The function takes one item
# and return True if the item should. It is automatically called for each item in the sequence. You don’t
# have to initialize an accumulator or iterate with a for loop.
def keep_evens(nums):
new_seq = filter(lambda num: num % 2 == 0, nums)
return list(new_seq)
print(keep_evens([3, 4, 6, 7, 0, 1]))
# Output:
#[4, 6, 0]
# 1) Write code to assign to the variable filter_testing all the elements in lst_check that have a w in
# them using filter.
lst_check = ['plums', 'watermelon', 'kiwi', 'strawberries', 'blueberries', 'peaches', 'apples', 'mangos', 'papaya']
filter_testing = filter(lambda word: "w" in word, lst_check)
print(filter_testing)
# Output: ['watermelon', 'kiwi', 'strawberries']
# 2. Using filter, filter lst so that it only contains words containing the letter “o”. Assign to
# variable lst2. Do not hardcode this.
lst = ["witch", "halloween", "pumpkin", "cat", "candy", "wagon", "moon"]
lst2 = filter(lambda word: "o" in word, lst)
print(lst2)
# Output: ['halloween', 'wagon', 'moon']
@henryd0
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henryd0 commented Oct 16, 2022

lst_check = ['plums', 'watermelon', 'kiwi', 'strawberries', 'blueberries', 'peaches', 'apples', 'mangos', 'papaya']

filter_testing = list(filter(lambda have_w: 'w' in have_w , lst_check))

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