I am trying to fetch the smaller of one variable at one observation and a fixed number in a conditional dplyr::case_when statement in R. But the min() statement compares to the smallest observation of the entire variable vector, ie not for each observation.
library(tidyverse)
data_frame(spc = rep(c("cat", "dog"), 3), z = 1:6) %>%
mutate(
dogsmax3 = case_when(
spc == "dog" ~ min(z, 3),
TRUE ~ 0))
# spc z dogsmax3
# <chr> <int> <dbl>
#1 cat 1 0
#2 dog 2 1
#3 cat 3 0
#4 dog 4 1
#5 cat 5 0
#6 dog 6 1
While I look for a statement making this result:
# spc z dogsmax3
# <chr> <int> <dbl>
#1 cat 1 0
#2 dog 2 2
#3 cat 3 0
#4 dog 4 3
#5 cat 5 0
#6 dog 6 3
So, any suggestions for a better apprach?
Use rowwise
. Instead of case_when
you could also use an ifelse
:
library(tidyverse)
data_frame(spc = rep(c("cat", "dog"), 3), z = 1:6) %>%
rowwise() %>%
mutate(dogsmax3 = ifelse(spc == "dog", min(z,3), 0)) %>%
ungroup() ## to revert the grouping by rows
You can use ?pmin
instead of min
-
data_frame(spc = rep(c("cat", "dog"), 3), z = 1:6) %>%
mutate(
dogsmax3 = case_when(
spc == "dog" ~ pmin(z, 3),
TRUE ~ 0)
)
# A tibble: 6 x 3
spc z dogsmax3
<chr> <int> <dbl>
1 cat 1 0
2 dog 2 2.00
3 cat 3 0
4 dog 4 3.00
5 cat 5 0
6 dog 6 3.00
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