CSV format data manipulation: why use python scripts instead of MS excel functions?
After learning python, you are more flexible. The operations you can do with
on the user interface of MS excel are limited, whereas there are no limits 
if you use python.
The benefit is also, that you automate the modifications, e.g. you can re-use
it or re-apply it to a different dataset. The speed depends heavily on the
algorithm and library you use and on the operation.
You can also use VB script / macros in excel to automate things, but
usually python is less cumbersome and more flexible.
I am currently working on large data sets in csv format. In some cases, it is faster to use excel functions to get the work done. However, I want to write python scripts to read/write csv and carry out the required function. In what cases would python scripts be better than using excel functions for data manipulation tasks? What would be the long term advantages?