How to order data frame rows according to vector with specific order using R

Question

Is there any way available to ensure that a data frame's rows are ordered according to the required/target vector.

Consider the example below for reference?

data <- data.frame(alphabets = letters[1:4], value = c(rep(TRUE, 2), rep(FALSE, 2)))

data
#   alphabets value
# 1    a      TRUE
# 2    b      TRUE
# 3    c      FALSE
# 4    d      FALSE

target <- c("b", "c", "a", "d")

However, the method below seems to be a little bit complicated:

id <- sapply(target, function(x) {
    which(data$alphabets == x)
})
data <- data[id,]
rownames(data) <- NULL

data 
#   alphabets value
# 1    b      TRUE
# 2    c      FALSE
# 3    a      TRUE
# 4    d      FALSE

Answer 1

You can try using match:

data <- data.frame(alphabets=letters[1:4], value=c(rep(TRUE, 2), rep(FALSE, 2)))
target <- c("b", "c", "a", "d")
data[match(target, data$alphabets),]

  alphabets value
2    b      TRUE
3    c      FALSE
1    a      TRUE
4    d      FALSE

NOTE: It will work as long as your target/required  vector contains exactly the same elements as data$alphabets, and neither contains any duplicate values

match finds the row numbers that matches target's elements, and then we return data in that order.