matplotlib: format axis offset-values to whole numbers or specific number

Question

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

---

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?

Answer 1

I had exactly the same problem, and these lines fixed the problem:

from matplotlib.ticker import ScalarFormatter  y_formatter = ScalarFormatter(useOffset=False) ax.yaxis.set_major_formatter(y_formatter) 

Answer 2

A much easier solution is to simply customize the tick labels. Take this example:

from pylab import *  # Generate some random data... x = linspace(55478, 55486, 100) y = random(100) - 0.5 y = cumsum(y) y -= y.min() y *= 1e-8  # plot plot(x,y)  # xticks locs,labels = xticks() xticks(locs, map(lambda x: "%g" % x, locs))  # ytikcs locs,labels = yticks() yticks(locs, map(lambda x: "%.1f" % x, locs*1e9)) ylabel('microseconds (1E-9)')  show() 

Notice how in the y-axis case, I multiplied the values by 1e9 then mentioned that constant in the y-label

---

EDIT

Another option is to fake the exponent multiplier by manually adding its text to the top of the plot:

locs,labels = yticks() yticks(locs, map(lambda x: "%.1f" % x, locs*1e9)) text(0.0, 1.01, '1e-9', fontsize=10, transform = gca().transAxes) 

---

EDIT2

Also you can format the x-axis offset value in the same manner:

locs,labels = xticks() xticks(locs, map(lambda x: "%g" % x, locs-min(locs))) text(0.92, -0.07, "+%g" % min(locs), fontsize=10, transform = gca().transAxes)