使用python在csv文件中以特定方式添加列值

Question

i have a csv file similar to the following :

title  title2  h1  h2  h3 ... 
l1.1     l1     1   1   0  
l1.2     l1     0   1   0
l1.3     l1     1   0   1
l2.1     l2     0   0   1
l2.2     l2     1   0   1
l3.1     l3     0   1   1
l3.2     l3     1   1   0
l3.3     l3     1   1   0
l3.4     l3     1   1   0    

i want to be able to add the columns in the following manner:
h1 ( l1.1 + l1.2+ l1.3 ) = 2
h1 ( l2.1 + l2.2 ) = 1
h1 ( l3.1 + l3.2 + l3.3 +l3.4) = 3 and so on for every column And i want the final count for every such value as a summarised table :

title2  h1  h2  h3...
l1     2   2   1
l2     1   0   2
l3     3   4   1

how do i implement this?

Answer 1

Something like this should work. It takes an input in the form

title,title2,h1,h2,h3
l1.1,l1,1,1,0
l1.2,l1,0,1,0
l1.3,l1,1,0,1
l2.1,l2,0,0,1
l2.2,l2,1,0,1
l3.1,l3,0,1,1
l3.2,l3,1,1,0
l3.3,l3,1,1,0
l3.4,l3,1,1,0

and outputs

title2,h1,h2,h3
l1,2,2,1
l2,1,0,2
l3,3,4,1

Tested with Python 3.1.2. In Python 2.x you'll need to change the open() calls to use binary mode, and drop the newline="" bit). You can also drop the call to list() since in Python 2.x, map() already returns a list.

import csv
import operator

reader = csv.reader(open("test.csv", newline=""), dialect="excel")
result = {}

for pos, entry in enumerate(reader):
    if pos == 0:
        headers = entry
    else:
        if entry[1] in result:
            result[entry[1]] = list(map(operator.add, result[entry[1]], [int(i) for i in entry[2:]]))
        else:
            result[entry[1]] = [int(i) for i in entry[2:]]

writer = csv.writer(open("output.txt", "w", newline=""), dialect="excel")
writer.writerow(headers[1:])

keys = sorted(result.keys())
for key in keys:
    output = [key]
    output.extend(result[key])
    writer.writerow(output)

Answer 2

Have a look at the csv module. What you want to do is open the file with a csv.reader. Then you iterate over the file, one row at the time. You accumulate the results of the additions into a temporary list. When you are done, you write this list to a new csv.writer.

You might need to define a dialect as you are not really using CSV but some tab-delimited format.