HOw to store data in csvfile with spacific formate

hii every one.. i am doing one project in which i am working with x and y co-ordinates of mouse movments from mouse down event to up...

i store them in .csv file. i want the data to be store like this: from first mouse down to up x1-> 0.111,0.344,0.543... y1-> 0.867,0.645,0.856...

from second mouse down to up

x2-> 0.155,0.344,0.243... y2-> 0.367,0.445,0.656...

so i need my csv file should be like this:

x1 y1 x2 y2..

but i got it like

x1 y1 0 x2 0 y2

is it any way to remove these zeros and store from first column of each row...