Addition of errorbars in line graph in R (ggplot)

Question

I have been trying to create a graph that includes the replicates of some measurements (showed with points), the averages, and how they changed with time (showed with a line) and then I wanted to add errorbars to the graph. Here it is what I have:

A tibble called brixtwenty that has all the data of all the replicates. These ones are the names of the columns: Treatment Days cc

This one is the data 
dput(brixtwenty)
structure(list(Treatment = c("control", "control", "control", 
"control", "control", "control", "control", "control", "control", 
"control", "control", "control", "control", "control", "control", 
"EM", "EM", "EM", "EM", "EM", "EM", "EM", "EM", "EM", "EM", "EM", 
"EM", "EM", "EM", "EM"), Brix = c("20", "20", "20", "20", "20", 
"20", "20", "20", "20", "20", "20", "20", "20", "20", "20", "20", 
"20", "20", "20", "20", "20", "20", "20", "20", "20", "20", "20", 
"20", "20", "20"), Days = c(1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 
4, 5, 5, 5, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5), cc = c(285.091399590441, 
258.04137922621, 158.919577827924, 666.610152272179, 592.054531152063, 
395.766563783474, 726.762264553872, 731.837900223478, 470.645533209648, 
606.49690396958, 740.720133098691, 464.116384721947, 406.655732539073, 
342.175727545533, 167.083656188129, 703.846110644974, 523.016679600599, 
535.618627097046, 461.764854893598, 500.47182351152, 465.279713162811, 
441.200628089279, 921.867730585244, 871.728015690802, 468.771771230955, 
851.874066968395, 982.927187232172, 1030.31118691569, 1144.31011951096, 
1159.25979680224)), row.names = c(NA, -30L), class = c("tbl_df", 
"tbl", "data.frame"))

btwsummary <- brixtwenty %>% 
group_by(Days, Treatment) %>% 
summarise(mean=mean(cc), sd=sd(cc))

graph <- ggplot(brixtwenty, aes(x=Days, y=cc, color=Treatment)) + 
geom_point() + 
geom_line(data = btwsummary, aes(x=Days, y=mean, color=Treatment))+
geom_errorbar(data=btwsummary, aes(ymin=mean-sd, ymax=mean+sd, color=Treatment))

Error: Aesthetics must be either length 1 or the same as the data (10): y

Without the part of the errorbar I get the graph with the dots and the lines for both treatments.

Could someone help me with this please?

Thank you!

Please provide your data in `dput()` format. Visit [How to make a great R reproducible example](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example). — UseR10085, Aug 02 '21 at 05:45
Thanks for the suggestion. I have added the data now. Let me know if there is something else I can do to make my post more clear! — Juli P, Aug 02 '21 at 06:27

score 0 · Answer 1 · answered Aug 02 '21 at 07:07

To get you started, read up on layer inheritance of ggplot. In many cases, a lower layer might be in conflict with an upper layer, in particular the upper layer aesthetics definition. What you can always do is specify explicitly in each layer what data and aesthetics you are working with. (I know a lot of people will tell you this is not the way to do it, but it makes sure you start with something that works, before you make it more elegant).

In your case:

library(ggplot2)

ggplot() +       # the basic ggplot canvas
    geom_point(data = brixtwenty, aes(x=Days, y=cc, color=Treatment)) +   # your points
    geom_line(data = btwsummary, aes(x=Days, y=mean, color=Treatment)) +  # your summary mid(mean)point line
    geom_errorbar(data = btwsummary, aes(x = Days, ymin = mean-sd, ymax=mean+sd, color = Treatment))  # the errorbars you want to show based on your btwsummary

This gives you:

Addition of errorbars in line graph in R (ggplot)

1 Answers1