matplotlib-users

[Matplotlib-users] What is the proper way to set y tick labels for a histogram ?

[Auré G. <aur...@ya...>]

Hi all,

I'm plotting the histogram of a data set:

x = datalist
bins= 100
hist(x,bins,normed=0)     #returns a tupple (n,bins,patches)

Rather trivial... but instead of the plotting the counts n, I'd like to plot the realtive percentage counts, i.e. n/len(x). I can't really use the option normed = 1 which plots n/(len(x)*dbins). I guess the simplest way would be to simply change the yticklabels (by dividing them by len(x)). The thing is that I simply cannot find out how to do this...

I tried using the axes.set_yticklabels() but doesn't work. I've also tried to find the child containing the label but couldn't find it (not in Axes, nor in YAxis etc...). I guess it must be a Text instance.

Can anyone give me a hint,

Cheers,

Aure




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Re: [Matplotlib-users] What is the proper way to set y tick labels for a histogram ?

[Antonio G. <ja...@ca...>]

Hi Aure,

You could try:

ax.set_yticklabels(ax.get_yticks()/len(x))


/Antonio



Auré Gourrier wrote:
> Hi all,
> 
> I'm plotting the histogram of a data set:
> 
> x = datalist
> bins= 100
> hist(x,bins,normed=0)    #returns a tupple (n,bins,patches)
> 
> Rather trivial... but instead of the plotting the counts n, I'd like to 
> plot the realtive percentage counts, i.e. n/len(x). I can't really use 
> the option normed = 1 which plots n/(len(x)*dbins). I guess the simplest 
> way would be to simply change the yticklabels (by dividing them by 
> len(x)). The thing is that I simply cannot find out how to do this...
> 
> I tried using the axes.set_yticklabels() but doesn't work. I've also 
> tried to find the child containing the label but couldn't find it (not 
> in Axes, nor in YAxis etc...). I guess it must be a Text instance.
> 
> Can anyone give me a hint,
> 
> Cheers,
> 
> Aure
> 
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Re: [Matplotlib-users] What is the proper way to set y tick labels for a histogram ?

[John H. <jd...@gm...>]

On Fri, Feb 22, 2008 at 7:52 AM, Auré Gourrier
<aur...@ya...> wrote:

> Rather trivial... but instead of the plotting the counts n, I'd like to plot
> the realtive percentage counts, i.e. n/len(x). I can't really use the option
> normed = 1 which plots n/(len(x)*dbins). I guess the simplest way would be
> to simply change the yticklabels (by dividing them by len(x)). The thing is
> that I simply cannot find out how to do this...
>
> I tried using the axes.set_yticklabels() but doesn't work. I've also tried
> to find the child containing the label but couldn't find it (not in Axes,
> nor in YAxis etc...). I guess it must be a Text instance.

You can set your own custom tick formatter:

import matplotlib.ticker as ticker

N = len(x)
def fmt_percent(x, pos=None):
    return '%1.2f'%(float(x)/N)

ax.xaxis.set_major_formatter(ticker.FuncFormatter(fmt_percent)).  See
http://matplotlib.sourceforge.net/examples/custom_ticker1.py for a
complete example.

JDH