# Apparent inconsistent plotting of histograms in Gadfly
**URL:** https://discourse.julialang.org/t/apparent-inconsistent-plotting-of-histograms-in-gadfly/77953
**Category:** Visualization
**Tags:** question, gadfly
**Created:** [March 16, 2022, 8:29am UTC](https://discourse.julialang.org/t/apparent-inconsistent-plotting-of-histograms-in-gadfly/77953 "2022-03-16T08:29:04Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@evan-wehi](https://discourse.julialang.org/u/evan-wehi)
#### Post date: [March 16, 2022, 8:29am UTC](https://discourse.julialang.org/t/apparent-inconsistent-plotting-of-histograms-in-gadfly/77953/1 "2022-03-16T08:29:04Z")
Why is the histogram for the WildType normalised data differently when plotted with other data compared to being plotted alone?
This plot command
```julia
plot(df[df.genotype .== "WildType", :], x=:level, Geom.histogram(bincount=200), Scale.x_log10, color=:genotype, Coord.cartesian(xmin=-2, xmax=1, ymin=0, ymax=8000)
```
produces this plot
while this plot
```julia
plot(df, x=:level, Geom.histogram(bincount=200), Scale.x_log10, color=:genotype, Coord.cartesian(xmin=-2, xmax=1, ymin=0, ymax=8000))
```
produces
The WildType data are roughly 3x larger in the second plot. This does not happen to the KO data if I plot it by itself. Am I missing somethong about how Gadfly histograms work?
---
### Author:  [@evan-wehi](https://discourse.julialang.org/u/evan-wehi)
#### Post date: [March 16, 2022, 10:54pm UTC](https://discourse.julialang.org/t/apparent-inconsistent-plotting-of-histograms-in-gadfly/77953/2 "2022-03-16T22:54:00Z")
Here is a useable example the reproduces the behaviour.
```julia
using Distributions, Gadfly, DataFrames
d1 = Normal(0, 1)
d2 = Normal(1, 0.5)
x = rand(d1, 10000)
df = DataFrame(x=x, class="Class 1")
x = 0.5 .* rand(d2, 10000)
append!(df, DataFrame(x=x, class="Class 2"))
spike = -2.0 .* ones(500)
append!(df, DataFrame(x=spike, class="Class 2"))
h = plot(df[df.class .== "Class 1", :],
x=:x,
color=:class,
Geom.histogram(bincount=200),
Coord.cartesian(xmin=-4, xmax=4, ymin=0, ymax=1000)
)
display(h)
h = plot(df,
x=:x,
color=:class,
Geom.histogram(bincount=200),
Coord.cartesian(xmin=-4, xmax=4, ymin=0, ymax=1000)
)
display(h)
```
This produces:
It looks like it has plotted Class 1 as the sum of Class 1 and Class 2. Is this to be expected? Is there a way to turn this behaviour off?
---
### Author:  [@juliohm](https://discourse.julialang.org/u/juliohm)
#### Post date: [March 16, 2022, 10:58pm UTC](https://discourse.julialang.org/t/apparent-inconsistent-plotting-of-histograms-in-gadfly/77953/3 "2022-03-16T22:58:09Z")
@evan-wehi try to reach the Gadfly.jl maintainers in their community channels. They use Gitter instead of Discourse.
---
### Author:  [@evan-wehi](https://discourse.julialang.org/u/evan-wehi)
#### Post date: [March 18, 2022, 2:27am UTC](https://discourse.julialang.org/t/apparent-inconsistent-plotting-of-histograms-in-gadfly/77953/4 "2022-03-18T02:27:39Z")
My bad - I missed it in the documentation. This behaviour is intended and is controlled by the `position` argument in `Geom.histogram`. I need to use `position=:dodge`.
