Filling created feature with values I'm trying to improve accuracy. I created a few new features based on old features. So I need to fill new feature's empty cell with same values in order to equaling shapes.Then, I tried it with median and also with mean but nothing changed. Is there any method that I can apply these cells in order to improve accuracy?

for example, there is a feature named age
I created new 2 feature named age_1 and age_2 ,
age1 consisting of age &lt; 55 ,
age2 consisting of age > 55

therefore there is some empty cells in the new features and I have to fill these
If I understood your question right - 
you've created a new feature age&lt;55 - which gets True/False, hence, there is no need for the second feature since it has a perfect (negative) correlation with the first one (i.e False in every record that the other new feature got True..).

2 last notes:


Note that the second feature ain't addeing any new information to the first one.
Note that you've missed the recodes with age==55


I would suggest:

df['is_old'] = df['age'].apply(lambda x: x&gt;55)