Grouped ggplot2 barplot with missing error bars

Question

I am trying to figure out how to have error bars plotted for only some members of a group plot. For example, I have a data set defined as:

 new_frame <- data.frame(Parms = c("CAGR", "CAGR", "CAGR", 
                                   "CAGR", "CAGR", "DD", "DD",
                                   "DD","DD","DD"),
                         Values = c(28, 27.4, 26.9, 24.6, 27.9, 
                                    18.7, 19.2, 18.5, 19.2, 19.1),
                         Rebal = c(18, 19, 20, 21, 22,
                                   18, 19, 20, 21, 22),
                         sd = c(2.8, 2.3, 1.9, 2.9, 2.1, 0,0,0,0,0))

which gives for new_frame:

   Parms Values Rebal  sd
1   CAGR   28.0    18 2.8
2   CAGR   27.4    19 2.3
3   CAGR   26.9    20 1.9
4   CAGR   24.6    21 2.9
5   CAGR   27.9    22 2.1
6     DD   18.7    18 0.0
7     DD   19.2    19 0.0
8     DD   18.5    20 0.0
9     DD   19.2    21 0.0
10    DD   19.1    22 0.0

My ggplot2 statement is:

library(ggplot2)
ggplot(new_frame, aes(x=Rebal, y=Values, fill=Parms)) +
  geom_bar(position="dodge", stat="identity") + 
  geom_errorbar(aes(ymin=Values - sd, ymax=Values + sd),
  position=position_dodge(0.9), width=0.2) +
  ggtitle("           Variation With Rebalance Period”)

and the plot is:

My question is how to avoid plotting the null error ticks for the green bars. Putting 0’s into new_frame for the sd values for DD still draws the ticks, and putting NAs into those positions throws a ggplot error.

Setting the SD values to NA throws a ggplot error. "Error: (converted from warning) Removed 5 rows containing missing values (geom_errorbar).” ---- OK, I had options(warn = 2) set. Resetting to options(warn = 1) it runs with the NAs and gives no error bars for the NAs as desired, but gives a warning: "Warning: Removed 5 rows containing missing values (geom_errorbar)." — Ernie
– Ernie, Commented Feb 25, 2019 at 19:55
@Gregor Yours NA solution is better. You should post an answer with aes(ymin = Values - ifelse(sd == 0, NA, sd), ymax = Values + ifelse(sd == 0, NA, sd)) — pogibas
– pogibas, Commented Feb 25, 2019 at 20:05
I'll delete these comments here since I've added an answer, but want to make sure you see: if you add na.rm = TRUE to the layer there will be no warning. — Gregor Thomas
– Gregor Thomas, Commented Feb 25, 2019 at 20:11

pogibas · Accepted Answer · 2019-02-25 19:37:06Z

2

You can set geom_errorbar color where value == 0 to NA:

ggplot(new_frame, aes(Rebal, Values, fill = Parms)) +
    geom_bar(position = "dodge", stat = "identity") + 
    geom_errorbar(aes(ymin = Values - sd, ymax = Values + sd,
                      # Is SD 0 (returns logical value)
                      color = sd == 0),
                  position = position_dodge(0.9), width = 0.2) +
    # Set 0 SD color to NA
    scale_color_manual(values = c("black", NA), guide = FALSE)

answered Feb 25, 2019 at 19:37

pogibas

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1 Comment

Ernie Over a year ago

Your answer works the same as the NA suggestion, and it still throws a warning. So, I think simply setting the missing sd values to NA and living with the waring is the best solution.

Gregor Thomas · Accepted Answer · 2019-02-25 20:13:07Z

1

Set the 0 values to NA:

# in the data
new_frame$sd[new_frame$sd == 0] = NA

# or inline 
aes(ymin = Values - ifelse(sd == 0, NA, sd), ymax = Values + ifelse(sd == 0, NA, sd))

This will throw a warning by default. You can disable the warning by adding the argument na.rm = TRUE to geom_errorbar layer:

geom_errorbar(
    aes(ymin = Values - sd, ymax = Values + sd),
    na.rm = T,
    position = position_dodge(0.9),
    width = 0.2
  )

I appreciate the clever color = sd == 0 approach, but this is a more general way to do it that doesn't depend on what other aesthetics are in use. (E.g., if you had mapped a color aesthetic for the error bar, then you would need to pick a different aesthetic for that approach to work.)

edited Feb 25, 2019 at 20:13

answered Feb 25, 2019 at 20:07

Gregor Thomas

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