Python - Parsing through multiple lines of data from STDIN to store in standard array

Question

I have gone through the suggested similar questions, however appear to run into dead-ends; likely because perhaps I am not adequately explaining my problem. I am attempting to take some STDIN I have access to, which looks like so:

What I am having trouble with is taking the integers after the first line and storing them all into a standard Python array.

[80, 90, 29, 20]

The very first input on the first line will always be some integer 0 or 1, representing the disabling/enabling of some "special feature", any other integers are then input which must be stored to a standard array. As you can see, some integers have lines all to themselves while other lines may have several integers (blank lines should be completely ignored). I have been attempting to solve this using sys.stdin, since I know after stripping things it already makes the input into list objects, however to little avail. My code so far is as follows:

parse = True
arry = []
print('Special Feature?  (Give 0 to disable feature.)')
feature = input()
print('Please give the input data:')
while parse:
    line = sys.stdin.readline().rstrip('\n')
    if line == 'quit':
        parse = False
    else:
        arry.append(line)
print('INPUT DATA:', arry)

The 'quit' is my attempt at a backdoor I can type by hand since I also don't know how to check for EOF. I know this is very bare-bones (hardly much of anything), but what I effectively wish to produce as my output is this:

Special Feature?  (Give 0 to disable feature.)
> 0
Please give the input data:
> 80 90 29 20
INPUT DATA: [80, 90, 29, 20]

The lines marked with ">" are not printed, I'm simply demonstrating how the input is conceptually supposed to be read. Of course, any and all help is appreciated, I look forward to your thoughts!

score 1 · Accepted Answer · answered May 01 '20 at 23:20

You can iterate over sys.stdin (read more here).

For storing your numbers, just write any code that will extract them from the strings, and then append the numbers to a list.

Here is an example.

import sys
parse = True
arry = []
print('Special Feature?  (Give 0 to disable feature.)')
feature = input()
print('Please give the input data:')
for l in sys.stdin:
    arry += l.strip().split() 
print('INPUT DATA:', arry)

Create a new file, for example data:

0
1 2 3
4 5 6

Now try to run the program

$ python3 f.py < data
Special Feature?  (Give 0 to disable feature.)
Please give the input data:
INPUT DATA: ['1', '2', '3', '4', '5', '6']

Each of the numbers is read from the file.

My apologies, I neglected to mention that I wanted to print 'INPUT DATA:' with the actual integers and not their string representations. That wasn't any trouble to convert, however, so otherwise this answer was perfect for my needs. Thank you for the help! — The Popcultureman, May 01 '20 at 23:39

score 1 · Answer 2 · answered May 01 '20 at 23:32

If you really want to keep sys.stdin (despite input()), you can use this approach:

import sys

parse = True
arry = []
print('Special Feature?  (Give 0 to disable feature.)')
feature = input()
print('Please give the input data:')
while parse:
    line = sys.stdin.readline().rstrip('\n')
    if line == 'quit':
        parse = False
    elif line !='':
        arry += [int(x) for x in line.split()]
print('INPUT DATA:', arry)

Input:

Special Feature?  (Give 0 to disable feature.)
1
Please give the input data:
10

20

22


1 3 5 0

quit

Output (input numbers converted to integers):

INPUT DATA: [10, 20, 22, 1, 3, 5, 0]

This was wonderful; another user pointed out I can iterate over sys.stdin without needing to go through .readline() first. However, I do appreciate your maintaining my "backdoor" in the original while condition, as well as the list comprehension. Thank you! — The Popcultureman, May 01 '20 at 23:45

Python - Parsing through multiple lines of data from STDIN to store in standard array

2 Answers2