Divide dataframe column value by the total of the column

Question

My question might be too easy for many of you but since i'm a beginner with Python..

I want to have the % by value of a column containing 3 different possible values (1,0,-1) but by excluding one of the values in the column (which is -1).

I did this : (df['col_name']).sum()/len(df.col_name)

However it also counts the -1 in it, while i just want to have the % of the value 1/total sum, but without -1 in the total sum.

Thank you for your help.

Answer 1

For exclude values replace -1 to missing values:

df['col_name'].replace(-1, np.nan).sum()/len(df.col_name) 

Or filter out -1 values if need count lengths of filtered Series:

np.random.seed(123)
df = pd.DataFrame({'col_name':np.random.choice([0,1,-1], size=10)})

print (df)
   col_name
0        -1
1         1
2        -1
3        -1
4         0
5        -1
6        -1
7         1
8        -1
9         1

s = df.loc[df['col_name'] != -1, 'col_name']
print (s)
1    1
4    0
7    1
9    1
Name: col_name, dtype: int32

print (s.sum()/len(s))
0.75

print (s.mean())
0.75