suppose I have the following dataframe:
import pandas as pd
df = pd.DataFrame({'return':[10, 28, 32, 50, 25]})
I want to set 25 (last element) to be 100 in a new column and then work backwards doing 50*100/25=200, 32*100/25=32*200/50=128..and so on
return index
0 25
1 28
2 32 128
3 50 200
4 25 100
Is there any way of doing this in -preferably- one line. Thanks!
df['index']=.... ???
Yeah it's possible with One line. Just use df['return'].iloc[-1] to get the last value of the return column and then simple do like below-
import pandas as pd
df = pd.DataFrame({'return':[10, 28, 32, 50, 25]})
df['index'] = (df['return'] * 100 / df['return'].iloc[-1]).astype(int)
print(df)
Output:
return index
0 10 40
1 28 112
2 32 128
3 50 200
4 25 100
int. Just here we have an int factor because 25 is a divisor of 100.intMaybe like this?
import pandas as pd
df = pd.DataFrame({'return':[10, 28, 32, 50, 25]})
last = df["return"].iloc[-1]
df['index'] = df['return'].apply(lambda x: x*(100/last))
df
It gives:
return index
0 10 40.0
1 28 112.0
2 32 128.0
3 50 200.0
4 25 100.0
last = df["return"].iloc[-1] and then df['index'] = df['return'].apply(lambda x: x*(100/last)) 
df['index'] = df['return'] * 4?