Check if all the characters in the list elements are letters

user2371563 0
Viewed 44

Below is code to get all the list elements containing characters. Is there any efficient way of doing the same thing?

ls = ['1a', 'b3', '1.45', 'apples', 'oranges', 'mangoes', 'apples.', 'apples+', 1,456,1.3,'apples-1']
finalls=[]

for l in ls:
    try:
        if l.isalpha():
            finalls.append(l)
    except AttributeError as e:
        pass
        # if str(l).isdigit():
        #     print("element is isdigit", l)
            
print(finalls)

['apples', 'oranges', 'mangoes'] # Desired Ouput
list python
3 Answers

First way:

ls = ['1a', 'b3', '1.45', 'apples', 'oranges', 'mangoes', 'apples.', 'apples+', 1,456,1.3,'apples-1']


new_lst = [a  for a in ls if str(a).isalpha()]
print(new_lst)

second way


from string import ascii_lowercase as letter

ls = ['1a', 'b3', '1.45', 'apples', 'oranges', 'mangoes', 'apples.', 'apples+', 1,456,1.3,'apples-1']

new_lst = list(filter(lambda e:all(a in letter+letter.upper() for a in str(e)),ls))

OUtput

['apples', 'oranges', 'mangoes']

Update you code

Don't add try-except just convert the element to string then check if it contains all letters.

ls = ['1a', 'b3', '1.45', 'apples', 'oranges', 'mangoes', 'apples.', 'apples+', 1,456,1.3,'apples-1']
finalls=[]

for l in ls:
    if str(l).isalpha():
        finalls.append(l)
            
print(finalls)
codester_090

Check the built-in filter function. It takes as first argument a function which is called for all elements and will yield only elements for which the function returns true.

For your example, this can be reduced to

ls = ['1a', 'b3', '1.45', 'apples', 'oranges', 'mangoes', 'apples.', 'apples+', 1,456,1.3,'apples-1']
finalls = list(filter(lambda e: isinstance(e, str) and e.isalpha(), ls))
print(finalls)

Note that you can iterate directly over the "result" of the filter function, you only need to convert it to a list if you really need the list. So a more typical example would not convert it to a list:

ls = ['1a', 'b3', '1.45', 'apples', 'oranges', 'mangoes', 'apples.', 'apples+', 1,456,1.3,'apples-1']
for fruit in filter(lambda e: isinstance(e, str) and e.isalpha(), ls)
    print(fruit)
treuss0

Why not simply use a list comprehension?

finalls = [x for x in ls if isinstance(x, str) and x.isalpha()]

List comprehensions are very fast. They are also clear and easy to read.

useregb30
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