CODEWITHSUNDEEP
python
Jay Dilla
Jay Dilla

Reputation: 79

trimming words in a list of strings

I'm writing some code that trims down a words in a list of string. if the last character of a word in the string is 't' or 's' it is removed and if the first character is 'x' it is removed.

words = ['bees', 'xerez']

should return:

['bee', 'erez']

So far my solution is:

trim_last = [x[:-1] for x in words if x[-1] == 's' or 't']

I think this trims the last characters fine. I then to trim the first characters if they are 'x' with this line: 

trim_first = [x[1:] for x in trim_last if x[0] == 'x']

but this just returns an empty list, can i some how incorporate this into one working line?

Upvotes: 1

Views: 273

Answers (7)

Aaditya Ura
Aaditya Ura

Reputation: 12679

Why you are using two list comprehension for that you can do with one list comprehension :

one line solution:

words = ['bees', 'xerez','hellot','xnewt']

print([item[:-1] if item.endswith('t') or item.endswith('s') else item for item in [item[1:] if item.startswith('x') else item for item in words]])

output:

['bee', 'erez', 'hello', 'new']

Explanation of above list comprehension :

final=[]
for item in words:
    sub_list=[]
    if item.endswith('t') or item.endswith('s'):
        sub_list.append(item[:-1])
    else:
        sub_list.append(item)
    for item in sub_list:
        if item.startswith('x'):
            final.append(item[1:])
        else:
            final.append(item)

print(final)

Upvotes: 0

John
John

Reputation: 1

You can try this code:

trim_last = [x.lstrip('x').rstrip('t').rstrip('s') for x in words]

Upvotes: 0

pktangyue
pktangyue

Reputation: 8534

[v.lstrip('x').rstrip('ts') for v in words]

Upvotes: 4

dabadaba
dabadaba

Reputation: 9532

If you are looking for a one-liner you can use some arithmetic to play with the list slicing:

words = ['bees', 'xerez', 'xeret']
[w[w[0] == 'x' : len(w) - int(w[-1] in 'st')] for w in words]
# output: ['bee', 'erez', 'ere']

Upvotes: 1

kabanus
kabanus

Reputation: 25980

Just to chime in - since this is in fact, a mapping:

map(lambda x: x[1:] if x[0] == 'x'  else x, words)

Upvotes: 1

RomanPerekhrest
RomanPerekhrest

Reputation: 92884

In one step with re.sub() function:

import re

words = ['bees', 'xerez']
result = [re.sub(r'^x|[ts]$', '', w) for w in words]

print(result)

The output:

['bee', 'erez']

Upvotes: 2

omu_negru
omu_negru

Reputation: 4770

You're doing a filter, not a mapping. The right way would be

trim_first = [x[1:] if x.startswith('x')  else x for x in trim_last]

Also, your solution should not return an empty list since the filter would match on the second element

Upvotes: 3

Related Questions