How to add manual colors for a ggplot2 (geom_smooth/geom_line)

Question

I want to built a plot with ggplot2. Therefore i use geom_line to visualize lines and geom_smooth to show the Min-Max-Range of a specific index. Two data frames were used, the first row consists of the date (e.g.: 2013-02-04) and the next are measured values (e.g. 2.532283).

First i generate an empty ggplot with all styles:

yrange_EVI2 = is the Range of the Index (Minimum - Maximum) xrange = is the date range for the x-Axis (earliest - latest date)

EVI2_veg <- ggplot() + geom_blank() + 
            ylim(yrange_EVI2) + xlim(xrange) +
            ggtitle("EVI2 for reference-data in Azraq (Jordan)") + ylab("EVI2") + xlab("month") +
            theme_bw(base_size = 12, base_family = "Times New Roman")

Second step is to plot the Ranges (Min-Max-Range) and lines with the mean for specific values:

EVI2_veg <- EVI2_veg +
            geom_smooth(aes(x=Date, y=Vegetable_mean, ymin=Vegetable_min, ymax=Vegetable_max), data=Grouped_Croptypes_EVI2, stat="identity") +
            geom_line(aes(x=Date, y=Tomato), data=Sample_EVI2_A_SPOT)

In the last step i tried to change the color with scale_fill_manual and scale_color_manual:

EVI2_veg <- EVI2_veg + 
             scale_fill_manual("Min-Max-Range and Mean \nof specific Croptypes",labels=c("Vegetable","Tomato"),values=c("#008B00","#FFFFFF")) +
             scale_color_manual("Min-Max-Range and Mean \nof specific Croptypes",labels=c("Vegetable","Tomato"),values=c("#008B00","#CD4F39"))

I read a lot of answers and the manuals for the specific packages but i don't understand when i use the different colors="" and fill="":

1. geom_line(ads(color="",fill=""))
2. geom_line(ads(),color="", fill="")
3. scale_color_manual(values=c("")) or scale_fill_manual=(values=c(""))

If i don't define the 1. no legend appears. But if i define it like in the Code the color don't match to the plot. Its my first time with ggplot2 and i read a lot of this useful package but i don't understand how i can define the colors. And how the colors from the plot and legend matching. It would be nice if somebody could help me.

Answer 1

First, it's always nice to include sample data with any plotting code otherwise we can't run it to see what you see. Please read how to make a great R reproducible example before making other posts. It will make it much easier for people to help you. Anyway, here's some sample data

Sample_EVI2_A_SPOT<-data.frame(
    Date=seq(as.Date("2014-01-01"), as.Date("2014-02-01"), by="1 day"),
    Tomato = cumsum(rnorm(32))
)
Grouped_Croptypes_EVI2<-data.frame(
    Date=seq(as.Date("2014-01-01"), as.Date("2014-02-01"), by="1 day"),
    Vegetable_mean=cumsum(rnorm(32))
)
Grouped_Croptypes_EVI2<-transform(Grouped_Croptypes_EVI2,
    Vegetable_max=Vegetable_mean+runif(32)*5,
    Vegetable_min=Vegetable_mean-runif(32)*5
)

And this should make the plot you want

EVI2_veg <- ggplot() + geom_blank() + 
    ggtitle("EVI2 for reference-data in Azraq (Jordan)") +
    ylab("EVI2") + xlab("month") +
    theme_bw(base_size = 12, base_family = "Times New Roman") + 
    geom_smooth(aes(x=Date, y=Vegetable_mean, ymin=Vegetable_min, 
        ymax=Vegetable_max, color="Vegetable", fill="Vegetable"),
        data=Grouped_Croptypes_EVI2, stat="identity") +
    geom_line(aes(x=Date, y=Tomato, color="Tomato"), data=Sample_EVI2_A_SPOT) +
    scale_fill_manual(name="Min-Max-Range and Mean \nof specific Croptypes",
        values=c(Vegetable="#008B00", Tomato="#FFFFFF")) +
    scale_color_manual(name="Min-Max-Range and Mean \nof specific Croptypes",
        values=c(Vegetable="#008B00",Tomato="#CD4F39"))
EVI2_veg

Note the addition of color= and fill= in the aes() calls. You really should put stuff you want in legends inside aes(). Here i specify "fake" colors that i then define them in the scale_*_manual commands.