Python中数据帧的条件采样

Question

I have a Dataframe of Names, Sex, Ages of individuals:

I would like to create a new Dataframe by sampling a fixed number of samples such that the average age of the new DataFrame is the same as the original DataFrame.

sample_df = pd.DataFrame({'Var':['A','B','C','D','E'] , 'Ages' : [22,35,43,18,NaN]})

sample_df
Out[410]: 
  Var  Ages
0   A    22
1   B    35
2   C    43
3   D    18
4   E    NaN

I would like to sample only 3 rows such that the age of 'E' is equal to the mean of A,B,C,D

Answer 1

Consider an indefinite iteration using while True then break after needs are met but depending on the variability of your data, this may take some time to process. Below builds a list of 100-row samples and breaks after ten samples are achieved.

samples = []

while True:
   sample_df = df.sample(n = 100)

   if sample_df['Age'].mean() == df['Age'].mean():
      samples.append(sample_df)

   if len(samples) == 10:
      break