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Format axis offset-values to whole numbers or specific number

Asked 2010-09-09T14:09:11.183
100

I have a matplotlib figure which I am plotting data that is always referred to as nanoseconds (1e-9). On the y-axis, if I have data that is tens of nanoseconds, ie. 44e-9, the value on the axis shows as 4.4 with a +1e-8 as an offset. Is there anyway to force the axis to show 44 with a +1e-9 offset?

The same goes for my x-axis where the axis is showing +5.54478e4, where I would rather it show an offset of +55447 (whole number, no decimal - the value here is in days).

I've tried a couple things like this:

p = axes.plot(x,y)
p.ticklabel_format(style='plain')

for the x-axis, but this doesn't work, though I'm probably using it incorrectly or misinterpreting something from the docs, can someone point me in the correct direction?

Thanks, Jonathan

Problem illustration

I tried doing something with formatters but haven't found any solution yet...:

myyfmt = ScalarFormatter(useOffset=True)
myyfmt._set_offset(1e9)
axes.get_yaxis().set_major_formatter(myyfmt)

and

myxfmt = ScalarFormatter(useOffset=True)
myxfmt.set_portlimits((-9,5))
axes.get_xaxis().set_major_formatter(myxfmt)

On a side note, I'm actually confused as to where the 'offset number' object actually resides...is it part of the major/minor ticks?

python matplotlib xticks yticks
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1 Answer

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For the second part, without manually resetting all the ticks again, this was my solution:

class CustomScalarFormatter(ScalarFormatter):
    def format_data(self, value):
        if self._useLocale:
            s = locale.format_string('%1.2g', (value,))
        else:
            s = '%1.2g' % value
        s = self._formatSciNotation(s)
        return self.fix_minus(s)
xmajorformatter = CustomScalarFormatter()  # default useOffset=True
axes.get_xaxis().set_major_formatter(xmajorformatter)

obviously you can set the format string to whatever you want.

answered 2013-06-29T13:03:55.847

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