Sampling with the DataFrame/Dataset API

We can use the sampleBy to create a stratified sample without replacement. We can specify the fractions for the percentages of each value to be selected in the sample.

The size of the sample and the number of record of each type are shown here:

Next, we create a sample with replacement that selects a fraction of rows (10% of the total records) using a random seed. Using sample  is not guaranteed to provide the exact fraction of the total number of records in the Dataset. We also print out the numbers of each type of records in the sample:

In the next section, we will explore sampling methods using RDDs.