When using the ‘bar’ plot command, unit
information is lost when changing the units for a given axis. The attached
script demonstrates this.
This is not the case for line plots because of the use of
Line2D’s ‘recache’ method.
–James Evans
bar_units-1783549.py (913 Bytes)
While the script clearly reveals a bug, but I don't think it is the
recache method (or its absence) that is the culprit. Rather it is the
conversion of the Axe.bar arguments (left, bottom, etc...) to arrays
before they can get stored array in their respective Rectangle
instances. I removed this conversion, and bar now should create the
Rectangle instances with unit info intact.
But there is an additional problem -- bar specifies the width and
bottom as optional scalar arguments, and to be safe, I suggest you
pass in dimensional values for these as well when using a unitized bar
chart. Otherwise they will be scalar and will default to the current
units, which is probably not what you want under a unit change (your
bar widths will be different under changes of units).
Here is a modified test script that appears to be working properly
under svn (r3844) with my recent change:
from pylab import figure, show, nx
cms = cm *nx.arange(0, 10, 2)
bottom=0*cm
width=0.8*cm
fig = figure()
ax1 = fig.add_subplot(2,2,1)
ax1.bar(cms, cms, bottom=bottom)
ax2 = fig.add_subplot(2,2,2)
ax2.bar(cms, cms, bottom=bottom, width=width, xunits=cm, yunits=inch)
ax3 = fig.add_subplot(2,2,3)
ax3.bar(cms, cms, bottom=bottom, width=width, xunits=inch, yunits=cm)
ax3.set_xlim(3, 6) # scalars are interpreted in current units
ax4 = fig.add_subplot(2,2,4)
ax4.bar(cms, cms, bottom=bottom, width=width, xunits=inch, yunits=inch)
#fig.savefig('simple_conversion_plot.png')
ax4.set_xlim(3*cm, 6*cm) # cm are converted to inches
show()
On 9/11/07, James Evans <jrevans1@...310...> wrote:
When using the 'bar' plot command, unit information is lost when changing
the units for a given axis. The attached script demonstrates this.
This is not the case for line plots because of the use of Line2D's 'recache'
method.