Fixing the order of facets in ggplot when using dplyr to transform data to long form

Question

I got help here yesterday to create a facet grid of multiple columns. This yielded a large grid containing 8*5 plots. The code creates a combination of plot for various Outcomes * Responses. For example (Outcome1 * Response1, Outcome1 * Response2, Outcome3 * Response1, Outcome2 * Response1 and so on).

I have pasted the code below.

plot1 <- ancestralmeansindex %>%
gather(var1, value1, bicepind:wcind) %>%
gather(var2, value2, mmois:mpfat) %>%
ggplot(aes(x = value1, y = value2)) + 
geom_point(color='blue') +
geom_smooth(method = "lm", se = FALSE) +
facet_grid(var2 ~ var1, scales = "free", switch = "both",
         labeller = as_labeller(c(mmois = "Water (gms)",
                                  mkcal = "Caloric Intake",
                                  mprot = "Protein (gms)",
                                  mcarb = "Carb (gms)",
                                  mtfat = "Total Fat (gms)",
                                  msfat = "Saturated Fat (gms)",
                                  mmfat = "Mono S.Fat (gms)",
                                  mpfat = "Poly US.Fat (gms)",
                                  bicepind = "Bicep",
                                  tricepind = "Tricep",
                                  subind = "Subscapular",
                                  supind = "Suprailiac",
                                  weightind = "Weight",
                                  wcind = "Waist Circum"))) +
  labs(title = "Regression Plot Matrix of Mean Dietary Values with    Index Change 1", x = NULL, y = NULL) +
theme_bw() +
theme(strip.placement = "outside",
    strip.background = element_blank())
ggsave("Regression Plot 1.pdf", width = 210, height = 297, units = "mm", plot1)

This gives a very neat grid of all the possible combinations mentioned in the code. However, the graph prints the plots in alphabetical order (as it is reflected in the labeller/data). I would like to change this order for both var2 and var1.

I read in the help that this problem can be solved by assigning factor levels and choosing a given order. For example, this solution Fixing the order of facets in ggplot

How do I assign factor levels to variables that have been converted to long form by dplyr? Can this be done? Is there another solution?

Edit1 I tried the solution below, but I am running into an error. Reproducible example below.

set.seed(1)
dat <- data.frame(
  Outcome1 = sample(1:10),
  Outcome2 = sample(11:20),
  Outcome3 = sample(21:30),
  Response1 = sample(31:40),
  Response2 = sample(41:50),
  Response3 = sample(51:60)
)

dat %>%
  gather(var1, value1, Outcome1:Outcome3) %>%
  mutate(var1, recode("Outcome1" = "Bicep",
                      "Outcome2" = "Tricep",
                      "Outcome3" = "Subscapular")) %>%
  factor(var1, levels = c("Bicep",
                          "Tricep",
                          "Subscapular")) 
gather(var2, value2, Response1:Response3) %>% 
  mutate(var2, recode("Response1" = "Water (gms)", 
                      "Response2" = "Caloric Intake",
                      "Response3" = "Protein (gms)")) %>%
  factor(var2, levels = c("Water (cms)", 
                          "Caloric Intake",
                          "Protein (gms)")) %>%
  ggplot(aes(x = value1, y = value2)) + 
  geom_point(color='blue') +
  geom_smooth(method = "lm", se = FALSE) +
  facet_grid(var2 ~ var1, scales = "free", switch = "both",
             labeller = as_labeller(c(mmois = "Water (gms)",
                                      mkcal = "Caloric Intake",
                                      mprot = "Protein (gms)",
                                      bicepind = "Bicep",
                                      tricepind = "Tricep",
                                      subind = "Subscapular"))) +
  labs(title = "Regression Plot", x = NULL, y = NULL) +
  theme_bw() +
  theme(strip.placement = "outside",
        strip.background = element_blank())


Error in factor(., var1, levels = c("Bicep", "Tricep", "Subscapular",  : 
  object 'var1' not found

Error in gather(var2, value2, Response1:Response3) : 
  object 'var2' not found

Nova · Accepted Answer · 2018-09-27T17:37:20.097

1

Yes! It can be done. Use dplyr mutate to recode your var1 and var2 variables, then use factor to ensure the levels are in the right order. Then you won't need to use the labeler. Thanks to your reproducible example I was able to test my solution and fix the code!

 dat %>%
  gather(var1, value1, Outcome1:Outcome3) %>%
  mutate(var1 = recode(var1, "Outcome1" = "Bicep",
                      "Outcome2" = "Tricep",
                      "Outcome3" = "Subscapular")) %>%
  mutate(var1 = factor(var1, levels = c("Bicep",
                          "Tricep",
                          "Subscapular"))) %>% 
gather(var2, value2, Response1:Response3) %>% 
  mutate(var2 = recode(var2, "Response1" = "Water (gms)", 
                      "Response2" = "Caloric Intake",
                      "Response3" = "Protein (gms)"),
          var2 = factor(var2, levels = c("Water (gms)", 
                          "Caloric Intake",
                          "Protein (gms)"))) %>%
  ggplot(aes(x = value1, y = value2)) + 
  geom_point(color='blue') +
  geom_smooth(method = "lm", se = FALSE) +
  facet_grid(var2 ~ var1, scales = "free", switch = "both") +
  labs(title = "Regression Plot", x = NULL, y = NULL) +
  theme_bw() +
  theme(strip.placement = "outside",
        strip.background = element_blank())

edited Sep 27 '18 at 17:37

answered Sep 27 '18 at 15:58

Nova

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Thanks! Where would I add this line of code? After gather? – DiscoR Sep 27 '18 at 16:03
Yup, you can use another `%>%` to add both lines, then carry on with your ggplot. Let me know if you can't get it to work (after reading the help files for recode, of course :P). It would be helpful if you could provide a reproducible example, too! – Nova Sep 27 '18 at 16:47
Thanks, I tried doing this but get an error. Could you please have a look at the original post? I have added what you suggested. And the error I am getting. Many thanks. – DiscoR Sep 27 '18 at 16:53
This is the error Error in factor(., var1, levels = c("Bicep", "Tricep", "Subscapular", : object 'var1' not found – DiscoR Sep 27 '18 at 16:53
https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example – Nova Sep 27 '18 at 16:56
perfect try my edits. sorry my original answer was hastily written. – Nova Sep 27 '18 at 17:37
Many thanks for this, I have it in a correct order now. – DiscoR Sep 27 '18 at 18:14

Fixing the order of facets in ggplot when using dplyr to transform data to long form

1 Answers1