Question

I have a CSV file which I am processing and putting the processed data into a text file.
The entire data that goes into the text file is one big table(comma separated instead of space). My problem is How do I remember the column into which a piece of data goes in the text file?

For eg. Assume there is a column called ‘col’.
I just put some data under col. Now after a few iterations, I want to put some other piece of data under col again (In a different row). How do I know where exactly col comes? (And there are a lot of columns like this.)

Hope I am not too vague…

Answer 1

Go with a list of lists. That is:

[[col1, col2, col3, col4], # Row 1
 [col1, col2, col3, col4], # Row 2
 [col1, col2, col3, col4], # Row 3
 [col1, col2, col3, col4]] # Row 4

To modify a specific column, you can transform this into a list of columns with a single statement:

>>> cols = zip(*rows)
>>> cols
[[row1, row2, row3, row4], # Col 1
 [row1, row2, row3, row4], # Col 2
 [row1, row2, row3, row4], # Col 3
 [row1, row2, row3, row4]] # Col 4