Use pandas isna to locate missing values before deciding whether to remove, impute, or preserve their patterns as predictive signals. section 2.4.2
Count missing values by feature
data.isna().sum(axis=0) returns booleans for missing entries, then sums True as 1 and False as 0. In the Auto MPG data, mpg has 8 missing cases and horsepower has 6. section 2.4.2
(data.isna()
.sum(axis=0)
)
Inspect the runnable expression used to count missing samples across columns. section 2.4.2

