| lag {SparkR} | R Documentation |
Window function: returns the value that is offset rows before the current row, and
defaultValue if there is less than offset rows before the current row. For example,
an offset of one will return the previous row at any given point in the window partition.
lag(x, ...) ## S4 method for signature 'characterOrColumn' lag(x, offset = 1, defaultValue = NULL)
x |
the column as a character string or a Column to compute on. |
... |
further arguments to be passed to or from other methods. |
offset |
the number of rows back from the current row from which to obtain a value. If not specified, the default is 1. |
defaultValue |
(optional) default to use when the offset row does not exist. |
This is equivalent to the LAG function in SQL.
lag since 1.6.0
Other window_funcs: cume_dist,
dense_rank, lead,
ntile, percent_rank,
rank, row_number
## Not run:
##D df <- createDataFrame(mtcars)
##D
##D # Partition by am (transmission) and order by hp (horsepower)
##D ws <- orderBy(windowPartitionBy("am"), "hp")
##D
##D # Lag mpg values by 1 row on the partition-and-ordered table
##D out <- select(df, over(lag(df$mpg), ws), df$mpg, df$hp, df$am)
## End(Not run)