[R] Can't add error bars to existing line graph

[Jim Lemon]

Hi Bruno,
The interaction.plot function plots the _levels_ of the x.factor
argument, not the values of the variable that is coerced to a factor.
This means that the temperature locations on the x axis are c(1,2),
not c(12,17). The code below works for me:

readscaphfileNEW<-read.table(text="EXPERIMENT TEMP SCAPH.BPM
1        2021   12        82
2        2021   12        58
3        2021   12        78
4        2021   12        59
5        2021   12        80
6        2021   12       100
7        2021   12        61
8        2021   12       103
9        2021   12        61
10       2021   17       100
11       2021   17        70
12       2021   17        83
13       2021   17        73
14       2021   17       143
15       2021   17       103
16       2021   17        73
17       2021   17       158
18       2021   17        95
19       2021   17        80
20       1939   12       158
21       1939   12       148
22       1939   12       152
23       1939   12       148
24       1939   12       160
25       1939   12       168
26       1939   12       152
27       1939   12       150
28       1939   12       187
29       1939   17       300
30       1939   17       302
31       1939   17       291
32       1939   17       240
33       1939   17       253
34       1939   17       207
35       1939   17       184
36       1939   17       224
37       1939   17       242
38       1939   17       236",
header=TRUE,stringsAsFactors=FALSE)
interaction.plot(readscaphfileNEW$TEMP,
readscaphfileNEW$EXPERIMENT, readscaphfileNEW$SCAPH.BPM,
xlab = "Temperature (°C)", ylab = "Scaphognathite Rate (BPM)",
main = "Scaphognathite",
ylim = c(0,300), trace.label = "Year",
type = "b", pch = c(19,17), fixed = TRUE)
library(plotrix)
Scaphmeans <-as.vector(by(readscaphfileNEW$SCAPH.BPM,
 readscaphfileNEW[,c("EXPERIMENT","TEMP")],mean))
Scaphse = as.vector(by(readscaphfileNEW$SCAPH.BPM,
 readscaphfileNEW[,c("EXPERIMENT","TEMP")],std.error))
dispersion(c(1,1,2,2),Scaphmeans,Scaphse)

Note that you can get much the same plot using brkdn.plot (plotrix):

brkdn.plot(SCAPH.BPM~EXPERIMENT+TEMP,data=readscaphfileNEW,
 xlab="Temperature C",pch=c(1,2))
legend(15,160,c(1939,2021),pch=c(1,2))

Jim

On Thu, Jun 17, 2021 at 3:38 AM Bruno.Salonen <bruno.salonen using hotmail.com> wrote:
>
>
> Hi all,
>
> I'm trying to add error bars to an existing line graph in base R.
>
> The basic line graph comes up just fine, but it does not show my error
> bars...
>
> Data frame = readscaphfileNEW
> Plot name = SCAPHLINEGRAPHNEW
> x axis = TEMP
> y axis = SCAPH.BPM
> Tracer = Year (SAME AS 'EXPERIMENT)
> Scaphmeans = means of SCAPH.BPM
> Scaphse = standard error of SCAPH.BPM
>
> Here is the code..
>
> SCAPHLINEGRAPHNEW <- interaction.plot(readscaphfileNEW$TEMP,
> readscaphfileNEW$EXPERIMENT, readscaphfileNEW$SCAPH.BPM,
> xlab = "Temperature (°C)", ylab = "Scaphognathite Rate (BPM)",
> main = "Scaphognathite",
> ylim = c(0,300), trace.label = "Year",
> type = "b", pch = c(19,17), fixed = TRUE)
> arrows(SCAPHLINEGRAPHNEW,Scaphmeans+Scaphse,SCAPHLINEGRAPHNEW,Scaphmeans-Scaphse,code=3,
> angle=90, length=0.1)
>
> Why are my error bars not showing? Is the 'arrows' line wrong?
>
> Thanks a million for your help, everybody.
>
> Here is my data set:
>
> > readscaphfileNEW
>    EXPERIMENT TEMP SCAPH.BPM
> 1        2021   12        82
> 2        2021   12        58
> 3        2021   12        78
> 4        2021   12        59
> 5        2021   12        80
> 6        2021   12       100
> 7        2021   12        61
> 8        2021   12       103
> 9        2021   12        61
> 10       2021   17       100
> 11       2021   17        70
> 12       2021   17        83
> 13       2021   17        73
> 14       2021   17       143
> 15       2021   17       103
> 16       2021   17        73
> 17       2021   17       158
> 18       2021   17        95
> 19       2021   17        80
> 20       1939   12       158
> 21       1939   12       148
> 22       1939   12       152
> 23       1939   12       148
> 24       1939   12       160
> 25       1939   12       168
> 26       1939   12       152
> 27       1939   12       150
> 28       1939   12       187
> 29       1939   17       300
> 30       1939   17       302
> 31       1939   17       291
> 32       1939   17       240
> 33       1939   17       253
> 34       1939   17       207
> 35       1939   17       184
> 36       1939   17       224
> 37       1939   17       242
> 38       1939   17       236
>
> Bruno
>
>
>
> --
> Sent from: https://r.789695.n4.nabble.com/R-help-f789696.html
>
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