Write dictionary of lists to a CSV file

Question

I'm struggling with writing a dictionary of lists to a .csv file.

This is how my dictionary looks like:

dict[key1]=[1,2,3] dict[key2]=[4,5,6] dict[key3]=[7,8,9] 

I want the .csv file to look like:

key1  key2  key3 1     4     7   2     5     8 3     6     9 

At first I write the header:

outputfile = open (file.csv,'wb') writefile = csv.writer (outputfile) writefile.writerow(dict.keys()) 

So far so good... However, my problem is that I don't know how I could assign one list to the corresponding column. e.g.:

for i in range(0,len(dict[key1])):     writefile.writerow([dict[key1][i],dict[key2][i],dict[key3][i]) 

will randomly fill the columns. Another problem is, that I have to manually fill in the keys and can't use it for another dictionary with 4 keys.

Answer 1

If you don't care about the order of your columns (since dictionaries are unordered), you can simply use zip():

d = {"key1": [1,2,3], "key2": [4,5,6], "key3": [7,8,9]} with open("test.csv", "wb") as outfile:    writer = csv.writer(outfile)    writer.writerow(d.keys())    writer.writerows(zip(*d.values())) 

Result:

key3    key2    key1 7       4       1 8       5       2 9       6       3 

If you do care about order, you need to sort the keys:

keys = sorted(d.keys()) with open("test.csv", "wb") as outfile:    writer = csv.writer(outfile, delimiter = "\t")    writer.writerow(keys)    writer.writerows(zip(*[d[key] for key in keys])) 

Result:

key1    key2    key3 1       4       7 2       5       8 3       6       9