Hello, I have the following list
l=[[1,2,3,4],[5,6,7,8]]
and I want to generate a csv file something like this:
1 5
2 6
3 7
4 8
the code that I have worked on is this
with open("output.csv", "wb") as f:
writer = csv.writer(f)
writer.writerows(l)
but what it does is generate a csv file like this:
1,2,3,4
5,6,7,8
and what I really want is that each sublist is a column of the csv file I have already looked at several examples but none clarifies the doubt. I hope you can help me.
The best thing is that you use NumPy to be able to transpose the data comfortably and then write them in a CSV:
import numpy as np
l=[[1,2,3,4],[5,6,7,8]]
datos = np.asarray(l)
np.savetxt("output.csv", # Archivo de salida
datos.T, # Trasponemos los datos
fmt="%d", # Usamos números enteros
delimiter=",") # Para que sea un CSV de verdad
What you need is to interlace the sublists before sending them to the CSV file. It is done with the function zip and passing the list:
with open("output.csv", "wb") as f:
writer = csv.writer(f)
writer.writerows(zip(*l))
In python2 the function zip create a new list in memory, not as in python3 that create an iterator. If you are going to save a lot of data, it is more efficient than user itertools.izip :
import itertools
with open("output.csv", "wb") as f:
writer = csv.writer(f)
writer.writerows(itertools.izip(*l))