# 9.15:  Drop rows or columns that contain missing values.  Use .dropna() with axis and thresh
# parameters to control behavior.

print('dataframe "sj":')
sj
print()

print('sj.dropna():')
sj.dropna()            # drop rows with any NaN
print()

print('sj.dropna(axis=1)')
sj.dropna(axis=1)      # drop columns with any NaN
print()

print('sj.dropna(thresh=5):')
sj.dropna(thresh=5)    # keep rows with at least 2 non-NaN values

