str2str (version 1.0.0)

rbind<-: Add Rows to Data Objects

Description

`rbind<-` adds rows to data objects as a side effect. The purpose of the function is to replace the need to use dat2 <- rbind(dat1, add1); dat3 <- rbind(dat2, add2); dat4 <- rbind(dat3, add3), etc. For data.frames, it functions similarly to `[<-.data.frame`, but allows you to specify the location of the rows similar to append (vs. c) and overwrite rows with the same rownames. For matrices, it offers more novel functionality since `[<-.matrix` does not exist.

Usage

rbind(data, after = nrow(data), row.nm = NULL, overwrite = TRUE) <- value

Value

Like other similar functions (e.g., `names<-` and `[<-`), `rbind<-` does not appear to have a return object. However, it technically does as a side effect. The argument data will have been changed such that value has been added as rows. If a traditional return object is desired, and no side effects, then it can be called like a traditional function: dat2 <- `rbind<-`(dat1, value = add1).

Arguments

data

data.frame or matrix of data.

after

either an integer vector with length 1 or a character vector of length 1 specifying where to add value. If an integer vector, it is the position of a row. If a character vector it is the row with that name. Similar to append, use 0L if you want the added rows to be first.

row.nm

character vector of length equal to NROW(value) that specifies the rownames of value once added to data as columns. This is an optional argument that defaults to NULL where the pre-existing rownames of value are used.

overwrite

logical vector of length 1 specifying whether rows from value or row.nm should overwrite rows in data with the same rownames. Note, if overwrite = FALSE, R will prevent repeat rownames by adding "1" to the end of the repeat rownames similar to rbind.

value

data.frame, matrix, or atomic vector to be added as rows to data. If a data.frame or matrix, it must have the same ncol as data. If an atomic vector, it must have length equal to ncol of data.

Details

Some traditional R folks may find this function uncomfortable. R is famous for limiting side effects, except for a few notable exceptions (e.g., `[<-` and `names<-`). Part of the reason is that side effects can be computationally inefficient in R. The entire object often has to be re-constructed and re-saved to memory. For example, a more computationally efficient alternative to rbind(dat) <- add1; rbind(dat) <- add2; rbind(dat) <- add3 is dat1 <- do.call(what = rbind, args = list(dat, add1, add2, add3)). However, `rbind<-` was not created for R programming use when computational efficiency is valued; it is created for R interactive use when user convenience is valued.

Similar to `rbind`, `rbind<-` works with both data.frames and matrices. This is because `rbind` is a generic function with a default method that works with matrices and a data.frame method that works with data.frames. Similar to `rbind`, if rownames of value are not given and row.nm is left NULL, then the rownames of the return object are automatically created and can be dissatisfying.

Examples

attitude2 <- attitude
rbind(attitude2) <- colMeans(attitude2) # defaults to rownames = as.character(nrow(`data`) + 1)
attitude2 <- attitude2[!(`%in%`(x = row.names(attitude2), table = "31")), ] # logical subset
rbind(attitude2, row.nm = "mean") <- colMeans(attitude2)
attitude2 <- attitude2[-1*(match(x = "mean", table = row.names(attitude2))), ] # position subset
rbind(attitude2, after = "10", row.nm = c("mean","sum")) <-
   rbind(colMeans(attitude2), colSums(attitude2)) # `value` as a matrix
attitude2 <- attitude2[grep(pattern = "mean|sum", x = row.names(attitude2),
   invert = TRUE), ] # rownames subset
attitude2 <- `rbind<-`(data = attitude2, value = colMeans(attitude2)) # traditional call
attitude2 <- as.matrix(attitude, rownames.force = TRUE) # as.matrix.data.frame
rbind(attitude2, after = "10", row.nm = "mean") <- colMeans(attitude2) # `data` as a matrix
# using overwrite
mtcars2 <- mtcars
rownames(mtcars2)
add <- mtcars[c("Mazda RX4","Mazda RX4 Wag","Datsun 710"), ]*11
rbind(mtcars2, overwrite = TRUE) <- add
mtcars2 <- mtcars
rbind(mtcars2, overwrite = FALSE) <- add