Returns subsets of WaterLevelDataFrames which meet conditions.
# S3 method for WaterLevelDataFrame subset(x, subset, select, drop = FALSE, ...)
object of class WaterLevelDataFrame.
logical expression indicating elements or rows to keep: missing values are taken as false.
expression, indicating columns to select from a data frame.
passed on to [ indexing operator.
further arguments to be passed to or from other methods.
An object similar to x, containing just the selected rows and columns. All other slots of the WaterLevelDataFrame remain unchanged.