Given this data:
df=data.frame(
x1=c(2,0,0,NA,0,1,1,NA,0,1),
x2=c(3,2,NA,5,3,2,NA,NA,4,5),
x3=c(0,1,0,1,3,0,NA,NA,0,1),
x4=c(1,0,NA,3,0,0,NA,0,0,1),
x5=c(1,1,NA,1,3,4,NA,3,3,1))
I want to create an extra column min for the rowwise minimal value of selected columns using dplyr. That's easy using the column names:
df <- df %>% rowwise() %>% mutate(min = min(x2,x5))
But I have a large df with varying column names so I need to match them from some string of values mycols. Now other threads tell me to use select helper functions, but I must be missing something. Here's matches:
mycols <- c("x2","x5")
df <- df %>% rowwise() %>%
mutate(min = min(select(matches(mycols))))
Error: is.string(match) is not TRUE
And one_of:
mycols <- c("x2","x5")
df <- df %>%
rowwise() %>%
mutate(min = min(select(one_of(mycols))))
Error: no applicable method for 'select' applied to an object of class "c('integer', 'numeric')"
In addition: Warning message:
In one_of(c("x2", "x5")) : Unknown variables: `x2`, `x5`
What am I overlooking? Should select_ work? It doesn't in the following:
df <- df %>%
rowwise() %>%
mutate(min = min(select_(mycols)))
Error: no applicable method for 'select_' applied to an object of class "character"
And likewise:
df <- df %>%
rowwise() %>%
mutate(min = min(select_(matches(mycols))))
Error: is.string(match) is not TRUE
This was a bit trickier. In case of SE evaluation you'd need to pass the operation as string.
mycols <- '(x2,x5)'
f <- paste0('min',mycols)
df %>% rowwise() %>% mutate_(min = f)
df
# A tibble: 10 × 6
# x1 x2 x3 x4 x5 min
# <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#1 2 3 0 1 1 1
#2 0 2 1 0 1 1
#3 0 NA 0 NA NA NA
#4 NA 5 1 3 1 1
#5 0 3 3 0 3 3
#6 1 2 0 0 4 2
#7 1 NA NA NA NA NA
#8 NA NA NA 0 3 NA
#9 0 4 0 0 3 3
#10 1 5 1 1 1 1