column_window_functions {SparkR}

R Documentation

Window functions for Column operations

Description

Window functions defined for Column.

Usage

cume_dist(x = "missing")

dense_rank(x = "missing")

lag(x, ...)

lead(x, offset, defaultValue = NULL)

nth_value(x, offset, ...)

ntile(x)

percent_rank(x = "missing")

rank(x, ...)

row_number(x = "missing")

## S4 method for signature 'missing'
cume_dist()

## S4 method for signature 'missing'
dense_rank()

## S4 method for signature 'characterOrColumn'
lag(x, offset = 1, defaultValue = NULL)

## S4 method for signature 'characterOrColumn,numeric'
lead(x, offset = 1, defaultValue = NULL)

## S4 method for signature 'characterOrColumn,numeric'
nth_value(x, offset, na.rm = FALSE)

## S4 method for signature 'numeric'
ntile(x)

## S4 method for signature 'missing'
percent_rank()

## S4 method for signature 'missing'
rank()

## S4 method for signature 'ANY'
rank(x, ...)

## S4 method for signature 'missing'
row_number()

Arguments

x	In lag and lead, it is the column as a character string or a Column to compute on. In ntile, it is the number of ntile groups.
...	additional argument(s).
offset	a numeric indicating number of row to use as the value
defaultValue	(optional) default to use when the offset row does not exist.
na.rm	a logical which indicates that the Nth value should skip null in the determination of which row to use

Details

cume_dist: Returns the cumulative distribution of values within a window partition, i.e. the fraction of rows that are below the current row: (number of values before and including x) / (total number of rows in the partition). This is equivalent to the CUME_DIST function in SQL. The method should be used with no argument.

dense_rank: Returns the rank of rows within a window partition, without any gaps. The difference between rank and dense_rank is that dense_rank leaves no gaps in ranking sequence when there are ties. That is, if you were ranking a competition using dense_rank and had three people tie for second place, you would say that all three were in second place and that the next person came in third. Rank would give me sequential numbers, making the person that came in third place (after the ties) would register as coming in fifth. This is equivalent to the DENSE_RANK function in SQL. The method should be used with no argument.

lag: 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. This is equivalent to the LAG function in SQL.

lead: Returns the value that is offset rows after the current row, and defaultValue if there is less than offset rows after the current row. For example, an offset of one will return the next row at any given point in the window partition. This is equivalent to the LEAD function in SQL.

nth_value: Window function: returns the value that is the offsetth row of the window frame# (counting from 1), and null if the size of window frame is less than offset rows.

ntile: Returns the ntile group id (from 1 to n inclusive) in an ordered window partition. For example, if n is 4, the first quarter of the rows will get value 1, the second quarter will get 2, the third quarter will get 3, and the last quarter will get 4. This is equivalent to the NTILE function in SQL.

percent_rank: Returns the relative rank (i.e. percentile) of rows within a window partition. This is computed by: (rank of row in its partition - 1) / (number of rows in the partition - 1). This is equivalent to the PERCENT_RANK function in SQL. The method should be used with no argument.

rank: Returns the rank of rows within a window partition. The difference between rank and dense_rank is that dense_rank leaves no gaps in ranking sequence when there are ties. That is, if you were ranking a competition using dense_rank and had three people tie for second place, you would say that all three were in second place and that the next person came in third. Rank would give me sequential numbers, making the person that came in third place (after the ties) would register as coming in fifth. This is equivalent to the RANK function in SQL. The method should be used with no argument.

row_number: Returns a sequential number starting at 1 within a window partition. This is equivalent to the ROW_NUMBER function in SQL. The method should be used with no argument.

Note

cume_dist since 1.6.0

dense_rank since 1.6.0

lag since 1.6.0

lead since 1.6.0

nth_value since 3.1.0

ntile since 1.6.0

percent_rank since 1.6.0

rank since 1.6.0

row_number since 1.6.0

Examples

## Not run: 
##D # Dataframe used throughout this doc
##D df <- createDataFrame(cbind(model = rownames(mtcars), mtcars))
##D ws <- orderBy(windowPartitionBy("am"), "hp")
##D tmp <- mutate(df, dist = over(cume_dist(), ws), dense_rank = over(dense_rank(), ws),
##D               lag = over(lag(df$mpg), ws), lead = over(lead(df$mpg, 1), ws),
##D               percent_rank = over(percent_rank(), ws),
##D               rank = over(rank(), ws), row_number = over(row_number(), ws),
##D               nth_value = over(nth_value(df$mpg, 3), ws))
##D # Get ntile group id (1-4) for hp
##D tmp <- mutate(tmp, ntile = over(ntile(4), ws))
##D head(tmp)
## End(Not run)

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