How can I create a legend in ggplot which assigns names and colors to columns and not to values with-CodePudding

I have been looking up ideas to create legends in ggplot, yet all solutions only offer legends which divide the data of a single column in a dataframe in different groups by color and name with group = "columnname". This the head of the dataframe given:

ewmSlots	ewmValues	ewmValues2
1	0.7785078	0.7785078
2	0.7198410	0.7491744
3	0.7333798	0.7412771
4	0.9102729	0.8257750
5	0.7243151	0.7750450
6	0.8706777	0.8228614

Now I want a legend that shows ewmValues, ewmValues2 and ewmValues3 in their respective names and colors.

To give a simple example other solutions I found would resolve something like this

time	sex
lunch	male
dinner	female
dinner	male
lunch	female

where a legend would show sex and the colors to each sex, which is obviously not the issue I want to tackle here.

CodePudding user response：

What about just melting the data (let's call your above example a data frame named ewm)?

# With melt
ggplot(melt(ewm, id.vars = "ewmSlots"), aes(ewmSlots, value, color=variable, stat='identity'))  
  geom_line(size=1.4)   labs(color="")

If you are opposed to melting, the below gives the exact same thing:

# Without melt
ggplot(ewm, aes(ewmSlots))   
  geom_line(aes(y=ewmValues, color="ewmValues"), size=1.4)   
  geom_line(aes(y=ewmValues2, color="ewmValues2"), size=1.4)   
  geom_line(aes(y=ewmValues3, color="ewmValues3"), size=1.4)   
  labs(color="", y="value")