looping calculation in dataframe

[duncipe]

Hi,

I'm used to working with R but new to Python (except Think Python).
I wrote codes for various river cross section analysis in R and now want to transfer them to Python in order to compile them to executeables but I struggle with the first simple task:

I have a txt with the geometry as input (x being the lateral distance and y the elevation)

0,4
3,3
4,0
6,1
7,3
10,4

I want to calculate the area A for each step i: Ai= (yi+yi-1)*(xi-xi-1)/2

And store the value in a new column. How do I do this in Python? When storing x and y in seperate arrays, I'm struggling in adreessing them correctly in loops for example.
In R I could simply adress it i.e. data[i,1] or data[i-1,1]
Thank you

[buran]

there are different ways, depending on what libraries you use. What have you tried? Do you use external libraries like pandas, or do you use just modules from python standard library like csv

[duncipe]

I tried to go with numpy