Randomly Sample Rows from a Spark DataFrame
Draw a random sample of rows (with or without replacement) from a Spark DataFrame.
sdf_sample(x, fraction = 1, replacement = TRUE, seed = NULL)
- An object coercable to a Spark DataFrame.
- The fraction to sample.
- Boolean; sample with replacement?
- An (optional) integer seed.
Transforming Spark DataFrames
The family of functions prefixed with
sdf_ generally access the Scala
Spark DataFrame API directly, as opposed to the
dplyr interface which
uses Spark SQL. These functions will 'force' any pending SQL in a
dplyr pipeline, such that the resulting
returned will no longer have the attached 'lazy' SQL operations. Note that
the underlying Spark DataFrame does execute its operations lazily, so
that even though the pending set of operations (currently) are not exposed at
the R level, these operations will only be executed when you explicitly
collect() the table.