Python Whitespace Removal from Strings in a List

Question

Here is my program:

import sys
d = sys.stdin.readlines()
print(*d)
d = [x.strip(' ') for x in d]
print(*d)

Here is what happens when I run it:

>>> import program12 
Austin Houston 400
SanFrancisco            Fresno       700
Miami          Ames 500
# EOF
Austin Houston 400
 SanFrancisco            Fresno       700
 Miami          Ames 500

Austin Houston 400
 SanFrancisco            Fresno       700
 Miami          Ames 500

My program needs to accept per line, 2 Strings separated by white-space, followed (optionally) by a number. I want to separate these with no white-space so it would be:

['Austin', 'Houston', 400]

I then want to put these in a 'graph' so I would use something like:

flights = collections.defaultdict(dict)

Any help is appreciated!

EDIT: First answer is fixed! In reference to my previous question, I have added this code, and this generates an error: Now I have this:

import sys
d = sys.stdin.readlines()
print(*d)
d = [x.split() for x in d]
print(*d)
flights = {}
for each in d:
    flights[each.split()[0]][each.split()[1]] = each.split()[2]

And when I run:

>>> import program12
Austin Houston 400
SanFrancisco            Fresno       700
Miami          Ames 500
Austin Houston 400
 SanFrancisco            Fresno       700
 Miami          Ames 500

['Austin', 'Houston', '400'] ['SanFrancisco', 'Fresno', '700'] ['Miami', 'Ames', '500']
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/program12.py", line 8, in <module>
    flights[each.split()[0]][each.split()[1]] = each.split()[2]
AttributeError: 'list' object has no attribute 'split'

EDIT 2: My program:

import sys
import collections
d = sys.stdin.readlines()
d = filter(None,d.split('\n'))
flights = {each.split()[0]:{each.split()[1]:''} for each in d}
for each in d:
    sp = each.split();flights[sp[0]][sp[1]] = '' if len(sp) <= 2 else sp[2]

New Error:

>>> import program12
 Austin Houston 400
 SanFrancisco            Fresno       700
 Miami          Ames 500
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/program12.py", line 4, in <module>
    d = filter(None,d.split('\n'))
AttributeError: 'list' object has no attribute 'split'

Keerthana Prabhakaran · Accepted Answer · 2017-05-08 05:51:55Z

3

this is in correspondence with reference to your previous question too. str.split(' ') is different from str.split()

>>> d1 =  [i.split(' ') for i in filter(None,d.split('\n'))]
>>> d1
[['Houston', 'Washington', '', '', '', '', '', '', '', '1000'], ['Vancouver', 'Houston', '300'], ['Dallas', 'Sacramento', '', '', '', '', '', '', '', '', '', '800'], ['Miami', '', '', '', '', '', '', '', '', '', '', 'Ames', '2000'], ['SanFrancisco', 'LosAngeles'], ['ORD', 'PVD', '1000']]

>>> d2 =  [i.split() for i in filter(None,d.split('\n'))]
>>> d2
[['Houston', 'Washington', '1000'], ['Vancouver', 'Houston', '300'], ['Dallas', 'Sacramento', '800'], ['Miami', 'Ames', '2000'], ['SanFrancisco', 'LosAngeles'], ['ORD', 'PVD', '1000']]

Basically, you need to form your dict before accessing it!

>>> d
'\nHouston Washington        1000\nVancouver Houston 300\nDallas Sacramento          800\nMiami           Ames 2000\nSanFrancisco LosAngeles\nORD PVD 1000\n'
>>> d1=filter(None,d.split('\n'))
>>> flights = {each.split()[0]:{each.split()[1]:''} for each in d1}
>>>
>>> flights
{'Houston': {'Washington': ''}, 'SanFrancisco': {'LosAngeles': ''}, 'Dallas': {'Sacramento': ''}, 'Miami': {'Ames': ''}, 'Vancouver': {'Houston': ''}, 'ORD': {'PVD': ''}}
>>> for each in d1:sp = each.split();flights[sp[0]][sp[1]] = '' if len(sp) <= 2 else sp[2]
...
>>> flights
{'Houston': {'Washington': '1000'}, 'SanFrancisco': {'LosAngeles': ''}, 'Dallas': {'Sacramento': '800'}, 'Miami': {'Ames': '2000'}, 'Vancouver': {'Houston': '300'}, 'ORD': {'PVD': '1000'}}

edited May 8, 2017 at 5:51

answered May 8, 2017 at 5:28

Keerthana Prabhakaran

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13 Comments

Coder117 Over a year ago

Thank you! In reference to my previous question, now the second part of code you helped me with does not work. I have edited this question if you could please take a look! :)

Keerthana Prabhakaran Over a year ago

can you share the sample input for this?

Coder117 Over a year ago

I did. I included it at the end of this question.

Keerthana Prabhakaran Over a year ago

that is because, you have mentioned that you are using collections.defaultdict().. so there must be a dict with keys with default values before you can run the for loop

Aanchal1103 Over a year ago

@Coder117 You are using split on a list i.e. each and split cannot be used on a list.

|

JacobIRR · Accepted Answer · 2017-05-08 05:25:33Z

1

Use replace():

import sys
d = sys.stdin.readlines()
print(*d)
d = [x.replace(' ','') for x in d]
print(*d)

If there happen to be tabs instead of just spaces:

import sys
d = sys.stdin.readlines()
print(*d)
d = [x.replace(' ','').replace('\t', '') for x in d]
print(*d)

This matches the exact result you are trying to get

answered May 8, 2017 at 5:25

JacobIRR

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Comments

Mr. A · Accepted Answer · 2017-05-08 05:30:15Z

1

Try this

import sys
d = sys.stdin.readlines()
d = [i.strip() for x in d for i in x.split()]
print(*d)

if you want line by line

import sys
for d in sys.stdin.readlines():
    d = [i.strip() for i in d.split()]
    print(*d)

edited May 8, 2017 at 5:30

answered May 8, 2017 at 5:22

Mr. A

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Comments

Jon Kiparsky · Accepted Answer · 2017-05-08 05:32:35Z

1

Alternatively you could use a regex to split the lines:

import sys
import re
raw_lines = sys.stdin.readlines()
data = [re.split("\s+", line) for line in d]

"\s+" means "one or more whitespace characters" This does not address the problem of converting your (optional) number to a numeric format, but this seems like another question

answered May 8, 2017 at 5:32

Jon Kiparsky

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Comments

Aanchal1103 · Accepted Answer · 2017-05-08 05:35:10Z

1

For every line in d, strip newline characters using strip('\n') and then split it using split()

d = [x.strip().split() for x in d]

For your second question, for each in d: here d is a list of lists and so each is a list and you cannot use split() on it because it is already split. You can directly use each[0].

edited May 8, 2017 at 5:35

answered May 8, 2017 at 5:28

Aanchal1103

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