Hi all,
I wonder if there is a way to change the base used to calculate the
logarithmic mapping for graph.axis.logarithmic?
I have some random points generated uniformly on [0, 1] and then
mapped using an exponential function (which I'll paste in at the end
-- there is a factor of k which might seem strange but this mapping is
used by a trusted example in my problem domain!)
When I graph these points in PyX, they don't appear uniform on the
X-axis: if it's a linear axis, they are bunched on the left; if it's a
logarithmic axis, they are bunched on the right. I think if I could
set the base for the log axis to k, I could get the right result?
James
--
James McDermott
PhD candidate in Music Technology
CSG026,
Dept. Computer Science and Information Systems,
University of Limerick,
Ireland.
www.skynet.ie/~jmmcd
--
Here's an example program which demonstrates my problem:
--
#!/usr/bin/env python
from pyx import *
import random
import math
# map x from [0, 1] to [minv, maxv]
def exp_map(minv, maxv, x):
k = 5.0
return minv + (maxv - minv) * ((math.exp(k * x) - 1) / (math.exp(k) - 1))
r = [(exp_map(0.0, 10.0, random.random()), random.random())
for i in range(100)]
xaxes = [("lin", graph.axis.lin()), ("log", graph.axis.log())]
for name, xaxis in xaxes:
g = graph.graphxy(width=6, x=xaxis)
g.plot(graph.data.list(r, x=1, y=2))
g.writeEPSfile(name)
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