数据框中特定行的总和

Question

df = pd.DataFrame({'Tissues':['a1','x2','y3','b','c1','v2','w3'], 'M':[1,2,3,4,5,6,7], 'F':[8,9,10,11,12,13,14]})
df.set_index('Tissues')



Out[64]: 
         M   F
Tissues       
a1       1   8
x2       2   9
y3       3  10
b        4  11
c1       5  12
v2       6  13
w3       7  14

rem = ['a1', 'b', 'c1']

I'd like to get a new row 'rem' that get sums of rows with indexes in the list rem .

I can probably rename the indexes a1, b, c1 to 'rem', and then do groupby(df.index).sum() , but I am not sure how to rename all indexes to rem .

Answer 1

I don't think you need groupby

df.loc[rem].sum()

M    10
F    31

or

df.loc[rem].sum(axis=1)

Tissues
a1     9
b     15
c1    17

Answer 2

Use .loc:

df = df.set_index('Tissues')
df.loc['rem'] = df.loc[rem].sum()
print(df)

Output

          M   F
Tissues        
a1        1   8
x2        2   9
y3        3  10
b         4  11
c1        5  12
v2        6  13
w3        7  14
rem      10  31

Answer 3

You can try

df = df.set_index('Tissues')
x = pd.Series(df[df.index.isin(rem)].sum(), index=['M', 'F'], name="rem")
df.append(x)