How to reorder factor levels in a tidy way?

user_5410410 0
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Hi I usually use some code like the following to reorder bars in ggplot or other types of plots.

Normal plot (unordered)

library(tidyverse)
iris.tr <-iris %>% group_by(Species) %>% mutate(mSW = mean(Sepal.Width)) %>%
  select(mSW,Species) %>% 
  distinct()
ggplot(iris.tr,aes(x = Species,y = mSW, color = Species)) +
  geom_point(stat = "identity")

Ordering the factor + ordered plot

iris.tr$Species <- factor(iris.tr$Species,
                          levels = iris.tr[order(iris.tr$mSW),]$Species,
                          ordered = TRUE)
ggplot(iris.tr,aes(x = Species,y = mSW, color = Species)) + 
  geom_point(stat = "identity")

The factor line is extremely unpleasant to me and I wonder why arrange() or some other function can't simplify this. I am missing something?

Note:

This do not work but I would like to know if something like this exists in the tidyverse. 

iris.tr <-iris %>% group_by(Species) %>% mutate(mSW = mean(Sepal.Width)) %>%
  select(mSW,Species) %>% 
  distinct() %>% 
  arrange(mSW)
ggplot(iris.tr,aes(x = Species,y = mSW, color = Species)) + 
  geom_point(stat = "identity")
dplyr tidyverse ggplot2 r
4 Answers

If you happen to have a character vector to order, for example:

iris2 <- iris %>% 
    mutate(Species = as.character(Species)) %>% 
    group_by(Species) %>% 
    mutate(mean_sepal_width = mean(Sepal.Width)) %>% 
    ungroup()

You can also order the factor level using the behavior of the forcats::as_factor function :

"Compared to base R, this function creates levels in the order in which they appear"

library(forcats)
iris2 %>% 
    # Change the order
    arrange(mean_sepal_width) %>%  
    # Create factor levels in the order in which they appear
    mutate(Species = as_factor(Species)) %>%
    ggplot() +
    aes(Species, Sepal.Width, color = Species) +
    geom_point()

Notice how the species names on the x axis are not ordered alphabetically but by increasing value of their mean_sepal_width. Remove the line containing as_factor to see the difference.

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