将列表列表写入CSV，但仅获取密钥

Question

I have about 60 CSVs, each with 4 commons values that I need to extract and turn into one CSV. I've cut out a lot of info here, but confirmed that 'output_contents' has all the correct information, but it isn't being written when I call 'create_csv'.

        
def create_csv(list_of_lists):
    '''
    Writes the list of lists to a actual CSV file.

    PARAMS:
    list_of_lists - A list of keys, and each key is a list of values.

    RETURNS: None.

    OUTPUTS: A CSV file named "output.csv".
    '''
    print "Attempting to write CSV."
    with open("output.csv", "wb") as f:
        writer = csv.writer(f)
        writer.writerows(list_of_lists.keys())
        print "Write successful."

fileList = get_all_files(csv_directory)
get_csv_contents(fileList)

# Copy over the columns from the contents dictionary.
wanted_columns = ["key1", "key2", "key2", "key4",]

# Creates a key: value pair for every key and value in content as long as the key is a wanted column.
output_contents = {key: value for key, value in content.items() if key in wanted_columns}

create_csv(output_contents)

I've confirmed that output_contents has all the information from the input CSVs that is should.

When I run this, my output.csv looks like:

k,e,y,1
k,e,y,2
k,e,y,3
k,e,y,4

I know I'm making some small, silly error somewhere, but think my brain is fried and can't figure out where the hiccup is.

EDIT:

Here's runnable code.

import csv

def create_csv(list_of_lists):
    '''
    Writes the list of lists to a actual CSV file.

    PARAMS:
    list_of_lists - A list of keys, and each key is a list of values.

    RETURNS: None.

    OUTPUTS: A CSV file named "output.csv".
    '''
    print "Attempting to write CSV."
    with open("output.csv", "wb") as f:
        writer = csv.writer(f)
        writer.writerows(list_of_lists.keys())
        print "Write successful."



output_contents = {
       'key1': ["k1v1","k1v2","k1v3"],
       'key2': ["k2v1","k2v2","k2v3"],
       'key3': ["k3v1","k3v2","k3v3"],
       'key4': ["k4v1","k4v2","k4v3"],}

create_csv(output_contents)

Answer 1

The writerows method expects a list of iterables but you're providing a list of strings (which causes the function to iterate the string and consider each character as a value). So you should use instead...

output_contents = ((key, value) for key, value in content.items() if key in wanted_columns)

And in the create_csv function...

writer.writerows(list_of_lists)

Hope it helps!