Converting DataFrame values to int, adding them and create new column with result?

Question

I have a very large dataframe of string numbers, something like for example:

a,b,c
\"1\",\"2\",\"3\"
\"4\",\"5\",\"6\"
\"7\",\"8\",\"9\"

And I

Answer 1

In my opinion read_csv convert columns to integers.

So use:

df = pd.read_csv(file)
df['d'] = df['a'] + df['c']

But if failed, then try convert to integer or floats:

df = pd.read_csv(file)
df['d'] = df['a'].astype(int) + df['c'].astype(int)
#floats 
#df['d'] = df['a'].astype(float) + df['c'].astype(float)

If there are also some strings between numeric is possible convert problems values to NaNs and sum:

df = pd.read_csv(file)
df['d'] = pd.to_numeric(df['a'], errors='coerce') + pd.to_numeric(df['c'],  errors='coerce')