import pandas as pd

# Creating a DataFrame
df = pd.DataFrame({'A': [10, 0, 0, 1, 15], 'B': [4, 2, 6, 28, 8,],
    'C': [7, 1, 15, 10, 19]})

# Sort NaNs in the beginning
df.sort_values('A', ascending=True, inplace=True)

# Print sorted data frame
print(df)

>>>

    A   B   C
1   0   2   1
2   0   6  15
3   1  28  10
0  10   4   7
4  15   8  19