Expressing pandas subset using pipe

Question

I have a dataframe that I subset like this:

   a  b   x  y
0  1  2   3 -1
1  2  4   6 -2
2  3  6   6 -3
3  4  8   3 -4

df = df[(df.a >= 2) & (df.b <=          


        

Answer 1

You can try, but I think it is more complicated:

print df[(df.a >= 2) & (df.b <= 8)].groupby(df.x).mean()
     a  b  x    y
x                
3  4.0  8  3 -4.0
6  2.5  5  6 -2.5


def masker(df, mask):
    return df[mask]

mask1 = (df.a >= 2)
mask2 = (df.b <= 8)     

print df.pipe(masker, mask1).pipe(masker, mask2).groupby(df.x).mean()
     a  b  x    y
x                
3  4.0  8  3 -4.0
6  2.5  5  6 -2.5