collapse: roworder – R documentation

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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 = c("front","end","exchange"))

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.

Value

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

Note

If you don't require a copy of the data, use data.table::setorder (you can also use it in a piped call as it invisibly returns the data).

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

collapse

Advanced and Fast Data Transformation

v1.5.3

GPL (>= 2) | file LICENSE

Authors

Sebastian Krantz [aut, cre], Matt Dowle [ctb], Arun Srinivasan [ctb], Laurent Berge [ctb], Dirk Eddelbuettel [ctb], Josh Pasek [ctb], Kevin Tappe [ctb], R Core Team and contributors worldwide [ctb], Martyn Plummer [cph], 1999-2016 The R Core Team [cph]

Initial release

2021-03-05