How do I append values from a row in a CSV file into a list in python?

Question

If I have a csv file with only two rows containing an x and y coordinate, how would I go about taking row[0] and all its x points and appending them to a list?

In other words, lets say I have a list:

[[1,2], [3,5]]

Is there a way to take 1 and 3 and put them into a new list, and then 2 and 5 into another list?

So far I have only managed to get [[1,2], [3,5]], but my next step is wanting to adding the individual x and y. However, I realized that that is impossible if my list is in the form of list1 =[[1,2], [3,5]] — user152573
– user152573, Commented Jul 6, 2014 at 0:26

Joran Beasley · Accepted Answer · 2014-07-06 00:27:06Z

2

points = [[1,2], [3,5]] #[[x,y],[x,y]]
x,y = zip(*points) #x = [1,3],y=[2,5]

this is an easy way to transpose any 2d array (take the rows and change them to columns)

if you had 3d points for example

points = [[1,2,3],[2,3,4],[4,5,6]]
x,y,z = zip(*points)

you can get your points from the csv

points = list(csv.reader(open("my_file.csv")))

answered Jul 6, 2014 at 0:27

Joran Beasley

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2 Comments

user152573 Over a year ago

I'm sorry, what does zip(*points) do? I am wondering how I can take points from a row in excel and sum them up in python.

Joran Beasley Over a year ago

you said you had a list ... that list is points ... anyway theres one way to get your points out of a csv above ...

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