Thread: [Matplotlib-users] format yticks

Hi all,

how can I change the output format of yticks from 1000000 
to 1.e6 ?

Nils

On 24 March 2010 17:33, Nils Wagner <nw...@ia...> wrote:
> Hi all,
>
> how can I change the output format of yticks from 1000000
> to 1.e6 ?

I'm not sure if there's an easier way still, but this works:

from matplotlib.ticker import Formatter
class SciFormatter(Formatter):
    def __call__(self, x, pos=None):
        return "%0.2e" % x

ax = plt.gca()
ax.yaxis.set_major_formatter(SciFormatter())
plt.draw()

Angus.
-- 
AJC McMorland
Post-doctoral research fellow
Neurobiology, University of Pittsburgh

On Wed, Mar 24, 2010 at 8:03 PM, Angus McMorland <am...@gm...> wrote:
> On 24 March 2010 17:33, Nils Wagner <nw...@ia...> wrote:
>> Hi all,
>>
>> how can I change the output format of yticks from 1000000
>> to 1.e6 ?
>
> I'm not sure if there's an easier way still, but this works:
>
> from matplotlib.ticker import Formatter
> class SciFormatter(Formatter):
>    def __call__(self, x, pos=None):
>        return "%0.2e" % x
>
> ax = plt.gca()
> ax.yaxis.set_major_formatter(SciFormatter())
> plt.draw()

There's an easier way to format based on a string:

import matplotlib.pyplot as plt

#Also available in matplotlib.ticker namespace
sci_formatter = plt.FormatStrFormatter('%0.2e')
plt.gca().yaxis.set_major_formatter(sci_formatter)
plt.draw()


You can also make the default formatter (ScalarFormatter) display
scientific notation for smaller numbers (the default is anything with
an abs() >= 1e7). This displays in a slightly different way, with the
base power off to the side of the axis:

form = plt.gca().yaxis.get_major_formatter()

 # so anything with abs() >= 10000 will display in scientific notation
form.set_powerlimits((-4, 4))

plt.draw()


Ryan

-- 
Ryan May
Graduate Research Assistant
School of Meteorology
University of Oklahoma