Removing non numeric characters from text file Python 3.3

Question

I have been given the task to remove all non numeric characters including spaces from a text file and then print the new result next to the old characters for example:

Before:

sd67637 8

ssheiej44

After:

sd67637 8 = 676378

ssheiej44 = 44

As i am a beginner i do not know where to start with this task. I followed instructions from another user but i wasnt as clear to elaborate this is what i have so far.

text1 = open('/Users/student/Desktop/Harry.txt', 'r')
data = text1.readlines()
new_string = ''.join(ch for ch in data if ch.isdigit())
print(data, '=', new_string)

Yet it still doesnt give me the desired effect as shown above. Instead i get this:

    [] =

Could someone please fix this and explain in laymens terms please.

Just answered your [same question](http://stackoverflow.com/questions/17336943/removing-non-numeric-characters-from-a-string) - [here](http://stackoverflow.com/a/17337324/1561176) — Inbar Rose, Jun 27 '13 at 07:45
You are opening an empty file, or need to reopen it. If your code is printing `[]` for `data`, then `.readlines()` returned an *empty list*. — Martijn Pieters, Jun 27 '13 at 07:49

score 3 · Accepted Answer · answered Jun 27 '13 at 07:40

3

You did not call the text1.readlines method. Add ():

data = text1.readlines()

Note that a file object such as text1 can work as an iterator. There is no need to call .readlines(); just loop over text1 directly. Your code still needs adjustment; both .readlines() and text1 give you a sequence of lines:

for line in text1:
     new_string = ''.join(ch for ch in line if ch.isdigit())
     print(data, '=', new_string)

In your version, ch was assigned a whole line from the file at a time, and since each line contains at least a newline, .isdigit() would always be False.

answered Jun 27 '13 at 07:40

Martijn Pieters

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+1, I feel like `.readlines()` should just be removed due to all the confusion it generates. `list(f)` also works fine – jamylak Jun 27 '13 at 07:45
i did what martijin said now i get absolutley nothing in the console – Obcure Jun 27 '13 at 07:46
@Obcure: Did you reopen the file? – Martijn Pieters Jun 27 '13 at 07:47
@MartijnPieters yes ive even recreated a whole new file still no luck – Obcure Jun 27 '13 at 07:55
@Obcure: First make `print(open('....').read())` work; if you see data with that call, then you have a file with data. – Martijn Pieters Jun 27 '13 at 08:03
@MartijnPieters yes i did that copied it before the code you gave me so i get what is in the file but then blank after that – Obcure Jun 27 '13 at 08:13
And if you say `new_string = line`, comment out the other `new_string =` line, inside the loop, what is printed then? – Martijn Pieters Jun 27 '13 at 08:18
@MartijnPieters same as before – Obcure Jun 27 '13 at 08:21
let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/32460/discussion-between-obcure-and-martijn-pieters) – Obcure Jun 27 '13 at 08:24

score 0 · Answer 2 · edited May 23 '17 at 12:32

0

Pretty much the same answer I gave you on your previous question here.

from string import ascii_letters

with open('/Users/student/Desktop/Harry.txt') as f:
    for line in f:
        print (line, '=', line.translate(None, ascii_letters+' '))

edited May 23 '17 at 12:32

Community

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answered Jun 27 '13 at 07:49

Inbar Rose

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Removing non numeric characters from text file Python 3.3

2 Answers2