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R switch statement on comparisons

I'm trying to write an R script to evaluate different expressions based on fitting a value within ranges. The idea is that if Length is within one range, it will get evaluated one way, and if it's in a longer range it will get evaluated differently.

I can make this work with if/else statements, but it's pretty ugly, and I'm sure there must be a better way... here's code that works.

Length=8.2

if (Length<1) 
    mode="Walk"
else if (1<=Length & Length <5)
    mode="bike" 
else if (5<=Length & Length <10)
    mode="drive"
else if (Length>=10)
    mode="fly"

I've been trying to make something work with the switch function, but it seems to only work with text or integers... is there a way to have a switch statement that conducts evaluations at each case such as this?

Length=3.5

switch(Length,
       (Length<1)  mode="Walk"
       (1<=Length & Length <5)  mode="bike"
       (5<=Length & Length <10)  mode="drive"
       (Length=>10)  mode="fly"
)
like image 228
mooseo Avatar asked Sep 11 '12 23:09

mooseo


3 Answers

Here is a similar answer to Josh's, but using findInterval:

Length <- 0:11

cuts <- c(-Inf, 1, 5, 10, Inf)
labs <- c("Walk", "bike", "drive", "fly")

labs[findInterval(Length, cuts)]
# [1] "Walk"  "bike"  "bike"  "bike"  "bike"  "drive" "drive"
# [8] "drive" "drive" "drive" "fly"   "fly"

You can also use nested ifelse statements, it's a matter of taste:

ifelse(Length < 1,  "Walk",
ifelse(Length < 5,  "bike",
ifelse(Length < 10, "drive",
                    "fly")))
# [1] "Walk"  "bike"  "bike"  "bike"  "bike"  "drive" "drive"
# [8] "drive" "drive" "drive" "fly"   "fly"
like image 59
flodel Avatar answered Oct 19 '22 20:10

flodel


Using dplyr's case_when statement:

library(dplyr)
Length <- 3.5
mode <- case_when(
                Length < 1 ~ "Walk",
                1 <= Length & Length < 5 ~ "bike",
                5 <= Length & Length < 10 ~ "drive",
                Length >= 10 ~ "fly"
          )
mode
#> [1] "bike"
like image 30
shosaco Avatar answered Oct 19 '22 20:10

shosaco


Would cut() do what you need?

Length <- 0:11

cuts <- c(-Inf, 1, 5, 10, Inf)
labs <- c("Walk", "bike", "drive", "fly")

as.character(cut(Length, breaks = cuts, labels = labs, include.lowest=TRUE))
#  [1] "Walk"  "Walk"  "bike"  "bike"  "bike"  "bike"  "drive" "drive" "drive"
# [10] "drive" "drive" "fly"  
like image 21
Josh O'Brien Avatar answered Oct 19 '22 18:10

Josh O'Brien