collapse (version 1.8.9)

roworder: Fast Reordering of Data Frame Rows

Description

A fast substitute for dplyr::arrange. It returns a sorted copy of the data frame, unless the data is already sorted in which case no copy is made. In addition, rows can be manually re-ordered. Use data.table::setorder to sort a data frame without creating a copy.

Usage

roworder(X, ..., na.last = TRUE)
roworderv(X, cols = NULL, neworder = NULL, decreasing = FALSE,
          na.last = TRUE, pos = "front")

Value

A copy of X with rows reordered. If X is already sorted, X is simply returned.

Arguments

X

a data frame or list of equal-length columns.

...

comma-separated columns of X to sort by e.g. var1, var2. Negatives i.e. -var1, var2 can be used to sort in decreasing order of var1.

cols

select columns to sort by using a function, column names, indices or a logical vector. The default NULL sorts by all columns in order of occurrence (from left to right).

na.last

logical. If TRUE, missing values in the sorting columns are placed last; if FALSE, they are placed first; if NA they are removed (argument passed to radixorderv).

decreasing

logical. Should the sort order be increasing or decreasing? Can also be a vector of length equal to the number of arguments in cols (argument passed to radixorderv).

neworder

an ordering vector, can be < nrow(X). if pos = "front" or pos = "end", a logical vector can also be supplied. This argument overwrites cols.

pos

integer or character. Different arrangement options if !is.null(neworder) && length(neworder) < nrow(X).

Int.		String		Description
1		"front"		move rows in neworder to the front (top) of X (the default).
2		"end"		move rows in neworder to the end (bottom) of X.
3		"exchange"		just exchange the order of rows in neworder, other rows remain in the same position.
4		"after"		place all further selected rows behind the first selected row.

See Also

colorder, Data Frame Manipulation, Fast Grouping and Ordering, Collapse Overview

Examples

head(roworder(airquality, Month, -Ozone))
head(roworder(airquality, Month, -Ozone, na.last = NA))  # Removes the missing values in Ozone

## Same in standard evaluation
head(roworderv(airquality, c("Month", "Ozone"), decreasing = c(FALSE, TRUE)))
head(roworderv(airquality, c("Month", "Ozone"), decreasing = c(FALSE, TRUE), na.last = NA))

## Custom reordering
head(roworderv(mtcars, neworder = 3:4))               # Bring rows 3 and 4 to the front
head(roworderv(mtcars, neworder = 3:4, pos = "end"))  # Bring them to the end
head(roworderv(mtcars, neworder = mtcars$vs == 1))    # Bring rows with vs == 1 to the top