Ordering legend values ggplot-CodePudding

I was trying to ordering the labels of a plot but no matter what I do it doesn't change.

This is a dummy data frame because mine is way to big but I would get the same result

df <- data.frame(treatment= c("C", "3", "4", "5", "10","HT"), 
                 day1 = c(0.23, 0.16, 0.34, 0.21, 0.17,0.34),
                 day2=c(0.18,0.13,0.27,0.17,0.11,0.23),
                 day4=c(0.15,0.08,0.20,0.14,0.05,0.17))

I plot it using this code

df %>%
  pivot_longer(-treatment, names_to = "days", names_prefix = "day") %>% 
  mutate(days = as.integer(days),
         treatment = as.factor(treatment)) %>% 
  ggplot(aes(days, value, color = treatment))  
  geom_line() 
  ylab(expression(Transpiration (g/h))) xlab(expression(Days))  theme_dark()  theme(text = element_text(size = 20))

After this the legend order is 10,3,4,5,C,HT. So I tried to change to C,3,4,5,10,HT

df %>%
  pivot_longer(-treatment, names_to = "days", names_prefix = "day") %>% 
  mutate(days = as.integer(days),
         treatment = as.factor(treatment)) %>% 
  ggplot(aes(days, value, color = treatment))  
  geom_line() 
  ylab(expression(Transpiration (g/h))) xlab(expression(Days))  theme_dark()  theme(text = element_text(size = 20)) 
  scale_fill_discrete(breaks=c("C","3","4","5","10","HT"))

But I keep getting the same results. Any suggestions please? also how can I get the legend into the graph itself and delete the title of the legend. Thank you for all the help

CodePudding user response：

You can manually provide the limits to the scale if you want a particular order. Also you're using a fill legend for a colour aesthetic, which probably explains why your code wasn't working.

library(ggplot2)
library(tidyr)
library(dplyr)

df <- data.frame(treatment= c("C", "3", "4", "5", "10","HT"), 
                 day1 = c(0.23, 0.16, 0.34, 0.21, 0.17,0.34),
                 day2=c(0.18,0.13,0.27,0.17,0.11,0.23),
                 day4=c(0.15,0.08,0.20,0.14,0.05,0.17))

df %>%
  pivot_longer(-treatment, names_to = "days", names_prefix = "day") %>% 
  mutate(days = as.integer(days),
         treatment = as.factor(treatment)) %>% 
  ggplot(aes(days, value, color = treatment))  
  geom_line()  
  scale_colour_discrete(limits = df$treatment)

^{Created on 2021-10-06 by the reprex package (v2.0.1)}

To delete the title and place the legend inside the panel, you can use

  scale_colour_discrete(limits = df$treatment, name = NULL)  
  theme(legend.position = c(1, 1),
        legend.justification = c(1, 1))