Lost in transcription - 4 months ago 39

R Question

I have made a graph using ggplot from data I transformed into means with code:

`means<-ddply(shlf, .(Location), summarize, sal=mean(sal),temp=mean(temp), Calanus=mean(Calanus), Triconia=mean(Triconia))`

means

Location sal temp Calanus Triconia

1 bank_A 29.59429 7.642857 2217.971 20.417143

2 bank_B 29.20786 6.334286 1199.756 7.016429

3 bank_C 32.00357 7.000714 1504.554 37.397857

4 shelf_slope 35.07786 8.417143 5978.366 459.752857

5 shore_near 29.51643 7.053571 1412.179 49.303571

6 trough 34.46571 7.912143 2928.862 381.235714

and made the graph using this code:

`p1<-ggplot(means, aes(x = temp, y =Triconia , group = Location, color = Location)) +`

geom_line() +

geom_point(size = 5.0) +

ggtitle("Number of Triconia at different locations showing temp.") + ylab("Triconia (indv.)")+xlab("Temp. (Celsius)")+

theme_hc(bgcolor = "darkunica") +

scale_fill_hc("darkunica")

I would like to know if there is anyway I can add error bars to this graph. I know I have to transform the data to have more summaries but not sure how to proceed. Tried to do it seperately for each column but could'nt make a graph from it. like this:

`Temperature <- ddply(shlf, c("Location"), summarise,`

N = length(temp),

mean.temp = mean(temp),

sd = sd(temp),

se = sd / sqrt(N))

Any help is appreciated.

Answer

You are almost there. This is based on `se`

as provided in `Temperature`

data:

```
means$upper = Temperature$mean.temp + Temperature$se
means$lower = Temperature$mean.temp - Temperature$se
ggplot(means, aes(x = temp,
y = Triconia,
color = Location)) +
geom_point(size = 5.0) +
geom_errorbarh(aes(xmin = upper, xmax = lower))
```

Errorbar as a separate geom comes in distinct flavors: `geom_errorbar`

is vertical and `geom_errorbarh`

is horizontal; there are also things like `geom_crossbar`

, `geom_pointrange`

and the like. See `?geom_errorbar`

for help and some examples on all of them.