Number of bars in histogram - R
I have two problems with the histogram I'm making: I'm trying to generate an histogram in R, using the function hist(), for a frequency distribution of a numeric (interval) variable, which ranges from 0 to 10. The plot I'm aiming for should generate 11 bars. However:
Problem 1: My good friend R keeps plotting 10 bars.
Problem 2: Besides, I have no idea how to plot the "x" tick values in the proper way: below each bar, the category value in "x" (i.e., from 0 to 10). I have tried using axis(), as you can see below in my code, but I have no idea how to set this.
I'm pretty sure it is something quite basic, but I cannot find the solution to these two problems. To solve the first one, I thought setting breaks=11 would solve it, but it didn't work. I have no idea how to solve the second one.
This is my data (128 participants in a study, each scored a value between 0 and 10):
structure(list(ID_Esc_Def = c(915151L, 91494L, 1303553L, 1310117L,
1305411L, 1312263L, 1310121L, 1312264L, 1306498L, 1305413L, 1306497L,
1307521L, 1305409L, 1307523L, 1306491L, 1311366L, 1307532L, 915155L,
917111L, 915152L, 917120L, 1312267L, 1310119L, 1310114L, 1305414L,
1305412L, 1306494L, 1303559L, 1307526L, 917112L, 91496L, 1305410L,
1307527L, 917113L, 1307529L, 91491L, 1306495L, 1311363L, 1306493L,
1312260L, 1306496L, 91493L, 1303561L, 915153L, 1310118L, 1307530L,
1303557L, 1310113L, 1303556L, 1312259L, 1312258L, 91498L, 1311361L,
1311367L, 1311365L, 1306499L, 1312262L, 915149L, 915148L, 91492L,
1310120L, 1308168L, 1312266L, 1308167L, 1306492L, 1307531L, 1305408L,
1307514L, 1310116L, 1310112L, 1306490L, 1307525L, 1310115L, 1308174L,
1311368L, 915157L, 1312261L, 1308169L, 1312265L, 91495L, 1311360L,
1305417L, 91489L, 915154L, 1303555L, 91497L, 917118L, 131389L,
521390L, 521389L, 915150L, 131386L, 1305415L, 1311362L, 521386L,
131382L, 91490L, 521391L, 1305416L, 1303562L, 1311369L, 917116L,
521388L, 917114L, 1303558L, 521396L, 521387L, 1308172L, 131388L,
521395L, 131390L, 131384L, 917117L, 1311364L, 131387L, 1308173L,
917119L, 131385L, 917115L, 915156L, 521393L, 1308171L, 1308170L,
1303560L, 521392L, 131391L, 131383L, 1303554L), asig_dic = c(0L,
10L, 2L, 4L, 5L, 6L, 5L, 1L, 5L, 10L, 4L, 3L, 4L, 5L, 7L, 6L,
5L, 4L, 3L, 2L, 4L, 6L, 1L, 3L, 5L, 5L, 3L, 3L, 7L, 0L, 3L, 5L,
2L, 2L, 4L, 3L, 2L, 5L, 5L, 7L, 5L, 6L, 0L, 5L, 10L, 6L, 3L,
5L, 5L, 6L, 10L, 5L, 5L, 8L, 10L, 5L, 2L, 5L, 4L, 3L, 1L, 2L,
5L, 4L, 5L, 7L, 5L, 3L, 5L, 5L, 7L, 7L, 1L, 1L, 2L, 5L, 0L, 3L,
5L, 3L, 5L, 10L, 4L, 0L, 1L, 5L, 5L, 5L, 5L, 5L, 6L, 10L, 4L,
6L, 1L, 9L, 4L, 4L, 5L, 5L, 6L, 5L, 1L, 5L, 1L, 2L, 2L, 0L, 5L,
5L, 6L, 6L, 5L, 3L, 5L, 3L, 3L, 5L, 5L, 6L, 4L, 2L, 2L, 0L, 4L,
6L, 5L, 5L)), class = "data.frame", row.names = c(NA, -128L))
This is the code I'm using to generate the histogram:
m<-mean(dictator$asig_dic)
std<-sqrt(var(dictator$asig_dic))
quartz()
par(mfrow=c(1,1))
par(las=1)
hist(dictator$asig_dic, breaks = 11, col = "grey", freq = F, ylim=c(0,0.4), xaxt="n",
xlab="Generosity (Donated Tokens in DG)", ylab="Relative Frequency", main="")
curve(dnorm(x, mean=m, sd=std),
col="darkblue", lwd=2, add=TRUE, yaxt="n")
axis(1, at = seq(0, 10, by = 1), las=1)
As you can see, there are 10 bars. Any help?
All the best,
Mauricio.
Answer
One solution is to drink the ggplot2 Kool Aid. As you can see, there are 11 bins (as requested) and the labels are at the centre of the bars.
library(ggplot2)
library(ggthemes)
ggplot(dictator) +
geom_histogram(aes(x = asig_dic, y = (..count..)/sum(..count..)),
bins = 11, fill = "gray", colour = "black") +
stat_function(fun = dnorm,
args = list(mean = mean(dictator$asig_dic),
sd = sd(dictator$asig_dic)),
colour = "salmon", size = 1.25) +
theme_tufte() +
theme(axis.line = element_line(size = 1),
axis.text = element_text(size = 18),
axis.title = element_text(size = 20)) +
xlab("Generosity (Donated Tokens in DG)") +
ylab("Relative Frequency") +
scale_x_continuous(breaks = 0:10)
