align arrays with python

Question

I have 3 files (file1.txt, file2.txt, file3.txt) that look like:

file1:

file2:

file3:

I want to align the zeros of the arrays I read from these files and get the sum of the values on the right, that is getting something like:

-7  ->  12  + 0  + 0  =  12
-6  ->  13  + 0  + 0  =  13
-5  ->  11  + 13 + 0  =  24
-4  ->  10  + 4  + 0  =  14
-3  ->  4   + 5  + 0  =  9
-2  ->  8   + 4  + 3  =  15
-1  ->  7   + 7  + 14 =  28
0   ->  9   + 6  + 8  =  23
1   ->  10  + 9  + 7  =  26
2   ->  0   + 10 + 3  =  13
3   ->  0   + 2  + 9  =  11
4   ->  0   + 0  + 10 =  10
5   ->  0   + 0  + 8  =  8
6   ->  0   + 0  + 3  =  3
7   ->  0   + 0  + 0  =  0

How could I do that, with Python? Thank you in advance.

Do you know how to read values from a file or are you stuck on that? — Alex Hall
– Alex Hall, Commented Apr 13, 2016 at 21:03
You can read each file to a dictionary with key = first column and value = second column. That should get you started.. — gidim
– gidim, Commented Apr 13, 2016 at 21:03

Julien Salinas · Accepted Answer · 2016-04-13 21:18:26Z

1

Just an idea but there would be a lot them:

import all those pairs into one list of pairs
create a second empty list of pairs
parse every pair of the first list and check if the first element of the pair is somewhere among the first elements of the pairs of the second list. If it already is then sum the second element of the pairs, otherwise just append the pair to the second list.

answered Apr 13, 2016 at 21:18

Julien Salinas

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Copy and Paste · Accepted Answer · 2016-04-13 21:33:15Z

From start to finish, assuming the intended output is csv, as well as the input files are csv delimited via ",". Output methods are very flexible however if something else was anticipated.

import petl

file1 = petl.fromcsv('file1.csv')
file1 = petl.pushheader(file1, ['position', 'value1'])
file2 = petl.fromcsv('file2.csv')
file2 = petl.pushheader(file2, ['position', 'value2'])
file3 = petl.fromcsv('file3.csv')
file3 = petl.pushheader(file3, ['position', 'value3'])


file1_joined_file2 = petl.outerjoin(file1, file2, key='position')
all_joined = petl.outerjoin(file1_joined_file2, file3, key='position')
all_joined = petl.convert(all_joined, 'value1', {None: 0})
all_joined = petl.convert(all_joined, 'value2', {None: 0})
all_joined = petl.convert(all_joined, 'value3', {None: 0})
all_joined = petl.convert(all_joined, ('position', 'value1', 'value2', 'value3'), int)
all_joined = petl.addfield(all_joined, 'sum', lambda rec: rec['value1'] + rec['value2'] + rec['value3'])
all_joined = petl.sort(all_joined, 'position')

print petl.lookall(all_joined)
petl.tocsv(all_joined, 'done.csv')

Output from the print above:

+----------+--------+--------+--------+-----+
| position | value1 | value2 | value3 | sum |
+==========+========+========+========+=====+
|       -7 |     12 |      0 |      0 |  12 |
+----------+--------+--------+--------+-----+
|       -6 |     13 |      0 |      0 |  13 |
+----------+--------+--------+--------+-----+
|       -5 |     11 |     13 |      0 |  24 |
+----------+--------+--------+--------+-----+
|       -4 |     10 |      4 |      0 |  14 |
+----------+--------+--------+--------+-----+
|       -3 |      4 |      5 |      0 |   9 |
+----------+--------+--------+--------+-----+
|       -2 |      8 |      4 |      3 |  15 |
+----------+--------+--------+--------+-----+
|       -1 |      7 |      7 |     14 |  28 |
+----------+--------+--------+--------+-----+
|        0 |      9 |      6 |      8 |  23 |
+----------+--------+--------+--------+-----+
|        1 |     10 |      9 |      7 |  26 |
+----------+--------+--------+--------+-----+
|        2 |      0 |     10 |      3 |  13 |
+----------+--------+--------+--------+-----+
|        3 |      0 |      2 |      9 |  11 |
+----------+--------+--------+--------+-----+
|        4 |      0 |      0 |     10 |  10 |
+----------+--------+--------+--------+-----+
|        5 |      0 |      0 |      8 |   8 |
+----------+--------+--------+--------+-----+
|        6 |      0 |      0 |      3 |   3 |
+----------+--------+--------+--------+-----+

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