plotting multiple lines in the same plot using ggplot in R

April 2, 2023

I need to draw multiple line graphs that has some grouping. My data is follows:

    roc_mj_cmb_t1= c(0.8115,0.8060,0.8114,0.8340,0.8789,0.8743,0.8807,0.8838,
                 0.7946,0.7904,0.8245,0.8198,0.8721,0.8686,0.8876,0.8763,
                 0.8204,0.8146,0.7982,0.8350, 0.7977,0.8021,0.8137,0.8176



)

roc_mj_lab= c(rep("Y1_uni_cmb_test1",4),rep("Y1_Joint_test1",4),
          rep("Y1_uni_cmb_test2",4),rep("Y1_Joint_test2",4),
          rep("Y1_uni_both_test1",4), rep("Y1_uni_both_test2",4))


settin=c("setting 1","setting 2","setting 3","setting 4","setting 1","setting 2","setting 3","setting 4"
         ,"setting 1","setting 2","setting 3","setting 4","setting 1","setting 2","setting 3","setting 4"
         ,"setting 1","setting 2","setting 3","setting 4","setting 1","setting 2","setting 3","setting 4")


data_mj=data.frame(settin,roc_mj_cmb_t1,roc_mj_lab)

Then I obtained the line plot using this code:

    ggplot(data=data_mj,
       aes(y=roc_mj_cmb_t1,x=settin, group=roc_mj_lab))+
  geom_line(
         aes(color=roc_mj_lab,linetype=roc_mj_lab))
+scale_color_manual(values = c("blue", "red", "blue", "red","blue", "red")
       )+ylim(0.75,0.9) +scale_linetype_manual(values=c("longdash", "solid","longdash", "solid",
                                                        "dotted","dotted"))

Here is my output:

In this plot, I need to draw the lines starting from "Y1_XXX_test1" with same color and "Y1_XXX_test2" with same color. The 3 plots within "Y1_XXX_test1" need to be differentiated using line type. Similar thing needs to be apply for "Y1_XXX_test2" as well.

But based on this code, I have got different colors than I specified. (Ex: lines with yellow, green and pink colors) What could be the reason for that?

>Solution :

One of your "+"’s is in the wrong location.
The + in this line: "+scale_color_manual.." needs to be at the end of the previous line.
When I cleaned up as below, I got your blue and red lines.

ggplot(data=data_mj,aes(y=roc_mj_cmb_t1,x=settin, group=roc_mj_lab))+
  geom_line(aes(color=roc_mj_lab,linetype=roc_mj_lab)) +
  scale_color_manual(values = c("blue", "red", "blue", "red","blue", "red"))+
  ylim(0.75,0.9) +
  scale_linetype_manual(values=c("longdash", "solid","longdash", "solid","dotted","dotted"))