On Monday 18 December 2006 13:29, David L Goldsmith wrote:
> Simson Garfinkel wrote:
> > It really depends on your audience as to whether or not 1,000,000
> > through 9,000,000 is better displayed in scientific notation or not.
> > For audiences that I frequently present to, any scientific notation
> > is just unacceptable. You can add quantifiers (like KBps, MBps,
> > GBps), but presenting something a 5e+5 Bps will just be lost. You
> > *might* get away with e+3, e+6, and e+9, but never the other e's.
>
> Ah, "Engineering" notation - that could be a useful helper function.
A few months ago the question got asked on this very list.
The idea is to define a specific formatter. Here's what I'd come with (I copy
the initial post for convenience at the end of the message).
If it's found useful, I could put it in the cookbook (now that I remember how
to edit the wiki). Or I could leave our dear developers add it to the core.
P.
#----------------------------------------------
class EngrFormatter(ScalarFormatter):
"""A variation of the standard ScalarFormatter, using only multiples of
three
in the mantissa. A fixed number of decimals can be displayed with the optional
parameter `ndec` . If `ndec` is None (default), the number of decimals is
defined
from the current ticks.
"""
def __init__(self, ndec=None, useOffset=True, useMathText=False):
ScalarFormatter.__init__(self, useOffset, useMathText)
if ndec is None or ndec < 0:
self.format = None
elif ndec == 0:
self.format = "%d"
else:
self.format = "%%1.%if" % ndec
#........................
def _set_orderOfMagnitude(self, mrange):
"""Sets the order of margnitude."""
locs = N.absolute(self.locs)
if self.offset:
oom = math.floor(math.log10(mrange))
else:
if locs[0] > locs[-1]:
val = locs[0]
else:
val = locs[-1]
if val == 0:
oom = 0
else:
oom = math.floor(math.log10(val))
if oom <= -3:
self.orderOfMagnitude = 3*(oom//3)
elif oom <= -1:
self.orderOfMagnitude = -3
elif oom >= 4:
self.orderOfMagnitude = 3*(oom//3)
else:
self.orderOfMagnitude = 0
#........................
def _set_format(self):
"""Sets the format string to format all ticklabels."""
# set the format string to format all the ticklabels
locs = (N.array(self.locs)-self.offset) / 10**self.orderOfMagnitude +
1e-15
sigfigs = [len(str('%1.3f'% loc).split('.')[1].rstrip('0')) \
for loc in locs]
sigfigs.sort()
if self.format is None:
self.format = '%1.' + str(sigfigs[-1]) + 'f'
if self._usetex or self._useMathText:
self.format = '$%s$' % self.format
#..............................................................................
class MinimalFormatter(Formatter):
"""A minimal formatter: just the plain data !"""
def __init__(self,sigfigs=None):
if sigfigs is None:
self.fmt = "%f"
else:
self.fmt = "%.%if" % sigfigs
def __call__(self,x,pos=None):
return str(self.fmt % x).rstrip('0')
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