Python: Unique numbers in string

Question

I would like to retain the unique integer in the second column and print the entry in the previous (first) column. But I am having trouble converting a string to an integer and get the error: TypeError: 'int' object is not iterable

Input File

    A     1     108.80
    A     1       8.33
    B     2      45.10
    B     2       3.96
    B     2       3.94
    A     3       1.96
    A     3       2.94

Output

A
B
A

Script

with open('test.pdb') as infile:
        for line in infile:
                data = int(line.split()[1])
                seen = set()
                for number in range(data):
                        unique = [x for x in number if x not in seen]   
                        seen.update(unique)
                        print(unique)

What do you imagine `[x for x in number if x not in seen]` will give? Particularly `for x in number`, given that `number` is an `int` since you say `for number in range(data)`. — Alex Hall, Jun 29 '17 at 17:37
If youa re getting an error, post the full error message including the stack trace — juanpa.arrivillaga, Jun 29 '17 at 17:38
there is an error in your list comprehension `unique = [x for x in number if x not in seen]` , it is trying to loop over the variable `number` which is not a list in your case — Stack, Jun 29 '17 at 17:38
Possible duplicate of [Split an integer into digits to compute an ISBN checksum](https://stackoverflow.com/questions/974952/split-an-integer-into-digits-to-compute-an-isbn-checksum) — victor, Jun 29 '17 at 17:38

score 3 · Accepted Answer · answered Jun 29 '17 at 17:42

3

This is what you (probably) want:

seen = set()
with open('test.pdb') as infile:
    for line in infile:
        unique, data = line.split()[0:2]
        if data not in seen:
            print(unique)
            seen.add(data)

answered Jun 29 '17 at 17:42

Błotosmętek

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1

Yours is better! – dawg Jun 29 '17 at 17:43
1

rather than slicing `line.split()`, it's probably easier to use tuple unpacking (`unique, data, *_ = line.split()`) though that's only valid in Python3.4 (maybe 3.5?) or higher – Adam Smith Jun 29 '17 at 17:50

dawg · Answer 2 · 2017-06-29T17:52:30.657

1

Given that example, here is a list comprehension to process that:

with open(fn) as f:
    seen=set()
    print '\n'.join([c1 for c1,c2 in (line.split()[0:2] for line in f) 
                                   if not (c2 in seen or seen.add(c2))])

Prints:

A
B
A

edited Jun 29 '17 at 17:52

answered Jun 29 '17 at 17:41

dawg

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Python: Unique numbers in string

2 Answers2