change values in dataframe row based on condition
Question:
I have this dataframe
Region 2021 2022 2023
0 Europe 0.00 0.00 0.00
1 N.Amerca 0.50 0.50 0.50
2 N.Amerca 4.40 4.40 4.40
3 N.Amerca 0.00 8.00 8.00
4 Asia 0.00 0.00 1.75
5 Asia 0.00 0.00 0.00
6 Asia 0.00 0.00 2.00
7 N.Amerca 0.00 0.00 0.50
8 Eurpoe 6.00 6.00 6.00
9 Asia 7.50 7.50 7.50
10 Asia 3.75 3.75 3.75
11 Asia 3.50 3.50 3.50
12 Asia 3.80 3.80 3.80
13 Asia 0.00 0.00 0.00
14 Europe 6.52 6.52 6.52
Once a value in 2021 is found it should carry a 0 to the rest (2022 and 2023)
and if a value in 2022 is found -it should carry 0 to the rest. In other words, once value in found in columns 2021 and forth it should zero the rest on the right.
expected result would be:
Region 2021 2022 2023
0 Europe 0.00 0.00 0.00
1 N.Amerca 0.50 0.00 0.00
2 N.Amerca 4.40 0.00 0.00
3 N.Amerca 0.00 8.00 0.00
4 Asia 0.00 0.00 1.75
5 Asia 0.00 0.00 0.00
6 Asia 0.00 0.00 2.00
7 N.Amerca 0.00 0.00 0.50
8 Eurpoe 6.00 0.00 0.00
9 Asia 7.50 0.00 0.00
10 Asia 3.75 0.00 0.00
11 Asia 3.50 0.00 0.00
12 Asia 3.80 0.00 0.00
13 Asia 0.00 0.00 0.00
14 Europe 6.52 0.00 0.00
I have tried to apply a lambda:
def foo(r):
#if r['2021')>0: then 2020 and forth should be zero)
df = df.apply(lambda x: foo(x), axis=1)
but the challange is that there are 2021 – to 2030 and the foo becomes a mess)
Answers:
Let us try duplicated
df = df.mask(df.T.apply(pd.Series.duplicated).T,0)
Out[57]:
Region 2021 2022 2023
0 Europe 0.00 0.0 0.00
1 N.Amerca 0.50 0.0 0.00
2 N.Amerca 4.40 0.0 0.00
3 N.Amerca 0.00 8.0 0.00
4 Asia 0.00 0.0 1.75
5 Asia 0.00 0.0 0.00
6 Asia 0.00 0.0 2.00
7 N.Amerca 0.00 0.0 0.50
8 Eurpoe 6.00 0.0 0.00
9 Asia 7.50 0.0 0.00
10 Asia 3.75 0.0 0.00
11 Asia 3.50 0.0 0.00
12 Asia 3.80 0.0 0.00
13 Asia 0.00 0.0 0.00
14 Europe 6.52 0.0 0.00
This is another way:
df2 = df.set_index('Region').diff(axis=1).reset_index()
df2['2021'] = df['2021']
or:
df.iloc[:,1:].where(df.iloc[:,1:].ne(0).cumsum(axis=1).eq(1),0)
Output:
2021 2022 2023
0 0.00 0.0 0.00
1 0.50 0.0 0.00
2 4.40 0.0 0.00
3 0.00 8.0 0.00
4 0.00 0.0 1.75
5 0.00 0.0 0.00
6 0.00 0.0 2.00
7 0.00 0.0 0.50
8 6.00 0.0 0.00
9 7.50 0.0 0.00
10 3.75 0.0 0.00
11 3.50 0.0 0.00
12 3.80 0.0 0.00
13 0.00 0.0 0.00
14 6.52 0.0 0.00
I have this dataframe
Region 2021 2022 2023
0 Europe 0.00 0.00 0.00
1 N.Amerca 0.50 0.50 0.50
2 N.Amerca 4.40 4.40 4.40
3 N.Amerca 0.00 8.00 8.00
4 Asia 0.00 0.00 1.75
5 Asia 0.00 0.00 0.00
6 Asia 0.00 0.00 2.00
7 N.Amerca 0.00 0.00 0.50
8 Eurpoe 6.00 6.00 6.00
9 Asia 7.50 7.50 7.50
10 Asia 3.75 3.75 3.75
11 Asia 3.50 3.50 3.50
12 Asia 3.80 3.80 3.80
13 Asia 0.00 0.00 0.00
14 Europe 6.52 6.52 6.52
Once a value in 2021 is found it should carry a 0 to the rest (2022 and 2023)
and if a value in 2022 is found -it should carry 0 to the rest. In other words, once value in found in columns 2021 and forth it should zero the rest on the right.
expected result would be:
Region 2021 2022 2023
0 Europe 0.00 0.00 0.00
1 N.Amerca 0.50 0.00 0.00
2 N.Amerca 4.40 0.00 0.00
3 N.Amerca 0.00 8.00 0.00
4 Asia 0.00 0.00 1.75
5 Asia 0.00 0.00 0.00
6 Asia 0.00 0.00 2.00
7 N.Amerca 0.00 0.00 0.50
8 Eurpoe 6.00 0.00 0.00
9 Asia 7.50 0.00 0.00
10 Asia 3.75 0.00 0.00
11 Asia 3.50 0.00 0.00
12 Asia 3.80 0.00 0.00
13 Asia 0.00 0.00 0.00
14 Europe 6.52 0.00 0.00
I have tried to apply a lambda:
def foo(r):
#if r['2021')>0: then 2020 and forth should be zero)
df = df.apply(lambda x: foo(x), axis=1)
but the challange is that there are 2021 – to 2030 and the foo becomes a mess)
Let us try duplicated
df = df.mask(df.T.apply(pd.Series.duplicated).T,0)
Out[57]:
Region 2021 2022 2023
0 Europe 0.00 0.0 0.00
1 N.Amerca 0.50 0.0 0.00
2 N.Amerca 4.40 0.0 0.00
3 N.Amerca 0.00 8.0 0.00
4 Asia 0.00 0.0 1.75
5 Asia 0.00 0.0 0.00
6 Asia 0.00 0.0 2.00
7 N.Amerca 0.00 0.0 0.50
8 Eurpoe 6.00 0.0 0.00
9 Asia 7.50 0.0 0.00
10 Asia 3.75 0.0 0.00
11 Asia 3.50 0.0 0.00
12 Asia 3.80 0.0 0.00
13 Asia 0.00 0.0 0.00
14 Europe 6.52 0.0 0.00
This is another way:
df2 = df.set_index('Region').diff(axis=1).reset_index()
df2['2021'] = df['2021']
or:
df.iloc[:,1:].where(df.iloc[:,1:].ne(0).cumsum(axis=1).eq(1),0)
Output:
2021 2022 2023
0 0.00 0.0 0.00
1 0.50 0.0 0.00
2 4.40 0.0 0.00
3 0.00 8.0 0.00
4 0.00 0.0 1.75
5 0.00 0.0 0.00
6 0.00 0.0 2.00
7 0.00 0.0 0.50
8 6.00 0.0 0.00
9 7.50 0.0 0.00
10 3.75 0.0 0.00
11 3.50 0.0 0.00
12 3.80 0.0 0.00
13 0.00 0.0 0.00
14 6.52 0.0 0.00