rggplot2ggally

Ordering variables in the parallel coordinate plot in GGally for R

I am trying to order the variables in the parallel coordinate plot as below. But it throws an error and I am not so sure what causes this problem.

library(GGally)
library(palmerpenguins)

penguins %>% ggparcoord(columns = 3:4, groupColumn = 1, order = "anyClass")

The error says

Error in model.frame.default(formula = x ~ as.factor(classVar == class.names[i]), : variable lengths differ (found for 'as.factor(classVar == class.names[i])')

Solution

  • The issue seems to be related to the fact that your columns= contain missings. One possible fix would be to manually drop the observations with missings before passing to ggparcoord:

    library(GGally)
#> Loading required package: ggplot2
#> Registered S3 method overwritten by 'GGally':
#>   method from   
#>   +.gg   ggplot2
library(palmerpenguins)

penguins %>%
  tidyr::drop_na(3:4) |> 
  ggparcoord(columns = 3:4, groupColumn = 1, order = "anyClass")