How to manipulate columns of a data frame

Question

I read data from a CSV file using rpy2's read_csv() which creates a DataFrame. Now I want to directly manipulate an entire column. What I tried so far:

from rpy2.robjects.packages import importr
utils = importr('utils')

df = utils.read_csv(logn, header=args.head, skip=args.skip)
df.rx2('a').ro / 10

which I expected to write back to the DataFrame which it apparently doesn't: df is not affected by this operation. So, another idea was

df.rx2('a') = df.rx2('a').ro / 10

but that produces an error that function calls are not assignable - which is not obvious to me since the LHS should return a Vector(?)

So what did I miss?

Answer 1

In Python function calls are indeed not assignable, which creates the necessity to adapt a little the R code.

Try:

df[df.names.index('a')] = df.rx2('a').ro / 10