Sort rows of a dataframe in descending order of NaN counts

Question

I\'m trying to sort the following Pandas DataFrame:

         RHS  age  height  shoe_size  weight
0     weight  NaN     0.0        0.0     1.0
1  shoe_size  N         


        

Answer 1

Here's a one-liner that will do it:

df.assign(Count_NA = lambda x: x.isnull().sum(axis=1)).sort_values('Count_NA', ascending=False).drop('Count_NA', axis=1)
#          RHS  age  height  shoe_size  weight
# 1  shoe_size  NaN     0.0        1.0     NaN
# 0     weight  NaN     0.0        0.0     1.0
# 2  shoe_size  3.0     0.0        0.0     NaN
# 3     weight  3.0     0.0        0.0     1.0
# 4        age  3.0     0.0        0.0     1.0

This works by assigning a temporary column ("Count_NA") to count the NAs in each row, sorting on that column, and then dropping it, all in the same expression.