geom_histogram, number of count
Sav Tan
I'm doing like this.
ggplot(TotCalc, aes(x=CO3,y=100*(..count../sum(..count..)))) +
ylab(ylabel) +
geom_histogram(colour = "darkblue", fill = "white", binwidth=20)
Is it possible to know a number of count for each bin?
I dont understand how binwidth works, I have 3123 value of CO3 and
1697 unique value for CO3, when I plot ggplot I have 25 bars.
Help me to understand please
Thank you
Dennis Murphy
(1) Save the plot to an object.
(2) Use ggplot_build() to extract the counts. An example below shows how.
(3) There is a default binwidth, but it doesn't mean that there will be exactly
30 bars every time; the shape of the data has something to do with how
many bins are created. You can always establish your own binwidth as
an argument to geom_histogram().
Example:
d <- data.frame(x = rnorm(3000))
g <- ggplot(d, aes(x, y = ..count../sum(..count..))) + geom_histogram()
> str(ggplot_build(g))
stat_bin: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.
List of 6
$ data :List of 1
..$ 1:List of 1
.. ..$ :'data.frame': 33 obs. of 11 variables:
.. .. ..$ y : num [1:33] 0 0.000667 0.001 0.001667 0.005 ...
.. .. ..$ ymin : num [1:33] 0 0 0 0 0 0 0 0 0 0 ...
.. .. ..$ ymax : num [1:33] 0 0.000667 0.001 0.001667 0.005 ...
.. .. ..$ x : num [1:33] -3.46 -3.24 -3.02 -2.79 -2.57 ...
.. .. ..$ xmin : num [1:33] -3.57 -3.35 -3.13 -2.9 -2.68 ...
.. .. ..$ xmax : num [1:33] -3.35 -3.13 -2.9 -2.68 -2.46 ...
.. .. ..$ count : num [1:33] 0 2 3 5 15 19 30 43 61 103 ...
.. .. ..$ ndensity: num [1:33] 0 0.00707 0.0106 0.01767 0.053 ...
.. .. ..$ ncount : num [1:33] 0 0.00707 0.0106 0.01767 0.053 ...
.. .. ..$ density : num [1:33] 0 0.00298 0.00448 0.00746 0.02239 ...
.. .. ..$ group : num [1:33] 1 1 1 1 1 1 1 1 1 1 ...
.. ..- attr(*, "dim")= int [1:2] 1 1
<snip>
# The key element in this case is the count component, but it's nested
# four layers deep. To access it, use
> ggplot_build(g)$data[[1]][[1]]$count
stat_bin: binwidth defaulted to range/30. Use 'binwidth = x' to adjust this.
[1] 0 2 3 5 15 19 30 43 61 103 130 164 210 197 243 283 236 252 232
[20] 197 188 122 100 61 33 31 18 7 6 5 2 2 0
# There are 33 bins in this histogram. Now specify the binwidth:
h <- ggplot(d, aes(x, y = ..count../sum(..count..))) +
geom_histogram(color = 'orange', binwidth = 0.5)
h
ggplot_build(h)$data[[1]][[1]]$count
[1] 0 3 17 56 130 286 438 578 549 452 300 115 55 15 6 0
Specifying binwidth = 0.5 in this example reduces the histogram to 16 bins.
Different binwidths will obviously change the number of bins and the shape of
the histogram.
BTW, if you get an unevenly rendered histogram, the issue is known to
the developers. Also, the ggplot_build() function may disappear in
some future version, so caveat emptor.
HTH,
Dennis
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Brandon Hurr
Sav Tan
Sav Tan
On Oct 17, 12:22 pm, Brandon Hurr <brandon.h...@gmail.com> wrote:
> Hard to say for certain what you are after and even harder when we don't
> have your data or a sample dataset to play with. You could use bin() to
> figure it out yourself. Small example follows.
>
> *> head(x)*
> *[1] 31.22613 113.72626 197.61921 100.80194 36.18743 85.19606*
> *> bin(x, binwidth=20)*
> * count x width ndensity ncount density*
> *1 0 -30 20 0.000000000 0.000000000 0.000000e+00*
> *2 6 -10 20 0.009009009 0.009009009 9.606148e-05*
> *3 26 10 20 0.039039039 0.039039039 4.162664e-04*
> *4 84 30 20 0.126126126 0.126126126 1.344861e-03*
> *5 236 50 20 0.354354354 0.354354354 3.778418e-03*
> *6 519 70 20 0.779279279 0.779279279 8.309318e-03*
> *7 666 90 20 1.000000000 1.000000000 1.066282e-02*
> *8 666 110 20 1.000000000 1.000000000 1.066282e-02*
> *9 523 130 20 0.785285285 0.785285285 8.373359e-03*
> *10 259 150 20 0.388888889 0.388888889 4.146654e-03*
> *11 98 170 20 0.147147147 0.147147147 1.569004e-03*
> *12 30 190 20 0.045045045 0.045045045 4.803074e-04*
> *13 10 210 20 0.015015015 0.015015015 1.601025e-04*
> *14 0 230 20 0.000000000 0.000000000 0.000000e+00*
Sav Tan
I have another question,
to have a number of count I can do like you said: ggplot_build(g)
$data[[1]][[1]]$count, and how can I plot this labels into my graph?
But first I'm calculate frequency 100*(..count../sum(..count..)) and
above each bar I want to plot this frequency if it is not 0.
Is it possible to do this?
Brandon Hurr
Hello Brandon,sorry for the probably dumb question, but to what library belongs the bin function?I can not execute it in my R version...tnx,
G.
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Winston Chang
Please provide a reproducible example: https://github.com/hadley/devtools/wiki/Reproducibility
