Use of switch() in R to replace vector values

Here is the correct way to vectorize a function, e.g. switch:

# Data vector:test <- c("He is",          "She has",          "He has",          "She is")# Vectorized SWITCH:foo <- Vectorize(vectorize.args = "a",                 FUN = function(a) {                   switch(as.character(a),                          "He is" = 1,                          "She is" = 1,                          "He has" = 2,                          2)})# Result:foo(a = test)  He is She has  He has  She is       1       2       2       1

I hope this helps.

You coud try

test_out <- sapply(seq_along(test), function(x) switch(test[x],  "He is"=1,  "She is"=1,  "He has"=2,  "She has"=2))

Or equivalently

test_out <- sapply(test, switch,  "He is"=1,  "She is"=1,  "He has"=2,  "She has"=2)

The vectorised form of if is ifelse:

test <- ifelse(test == "He is", 1,        ifelse(test == "She is", 1,        ifelse(test == "He has", 2,        2)))

or

test <- ifelse(test %in% c("He is", "She is"), 1, 2)

switch is basically a way of writing nested if-else tests. You should think of if and switch as control flow statements, not as data transformation operators. You use them to control the execution of an algorithm, eg to test for convergence or to choose which execution path to take. You wouldn't use them to directly manipulate data in most circumstances.