Question

I am trying to write the contents of a list to a single column in a csv file. While I have done this in the past, I am not able to get this script to work. Instead I all of the columns filled instead of the rows

#getting values for p vlue of 1%-100%        
a = [numpy.arange(.01,1.01,.01)]
for i in a:
    with open("GFOLD_Hisat2.csv", 'wb') as file3:
        filewriter = csv.writer(file3)
        filewriter.writerow(score(list1, list2, i))

Where score() is a function that outputs an integer

Any thoughts on what I should modify?

Answer 1

Ignoring the questions of what list1 and list2 are (they are irrelevant if score() returns a single integer), I think the problem lies in your loop structure.

Instead of

for i in a:
    with open("GFOLD_Hisat2.csv", 'wb') as file3:
        filewriter = csv.writer(file3)
        filewriter.writerow(score(list1, list2, i))

You probably want

with open("GFOLD_Hisat2.csv", 'wb') as file3:
    filewriter = csv.writer(file3)
    for i in a:
        filewriter.writerow((score(list1, list2, i),))

At present you are opening the file and creating a new writer for each value of i. Note that I have turned the result of score into a tuple.

In [8]: a = [1,2,3,4,5]
In [9]: with open('a.csv', 'wt') as f:
    wr = csv.writer(f)
    for i in a:
        wr.writerow((i,))
   ...:         
In [10]: !cat a.csv
1
2
3
4
5

I'm also not sure why you are opening the file with 'wb'

As Rob points out, you can just use a comprehension - avoiding the loop completely. My answer is focused on explaining the mistake in your existing code.

Also, if your output file is really only going to contain a single column there's little reason to use a csv.writer. Simply do the following

a = [1,2,3,4,5]
b = [score(list1, list2, i) for i in a]
with open('a.csv','wt') as f:
    f.writelines('\n'.join(map(str,b))

Answer 2

You have to change the order of the file opening and the loop:

a = [numpy.arange(.01,1.01,.01)]

with open("GFOLD_Hisat2.csv", 'wb') as file3:
    filewriter = csv.writer(file3)
    for i in a:
        filewriter.writerow(score(list1, list2, i))

Writing contents of list to single csv column

2 个答案: