Re: [PyX-user] Automatic logarithmic partitioner fails for small graph

[André W. <co...@wo...>]

Hi Alexis,

this is the expected behavior. The reason is, that (a) you need more 
then one number at an axis, (b) ranges are fixed if set at the axis, and 
(c) all automatic log axis "partitions" always include a label at value 
1 (i.e. 10^0). While any positive integer can be used as the step for 
the exponents (like 10^0, 10^2, 10^4, ..., or 10^0, 10^3, 10^6, ..., and 
so on) and an arbitrary range might be in use (i.e. not including 10^0), 
the logic remains that same. For your case numbers at 10^0 and 10^2 are 
a valid partition, but 10^1 and 10^3 are not. 10^1, 10^2, 10^3 is fine, 
too, but 10, 100 and 1000 is rejected in your case due to overlapping 
labels. (Changing the texter to write the numbers using exponents could 
help here.)

If you get the range from the data and allow PyX to extend the range (as 
done by default), it probably finds a reasonable solution. Also 
including 10^0 (i.e. 1) will likely help in many situations. However 
note that overlapping labels are always rejected. Hence for tiny graphs 
the automatic axis partitioning might fail and there is no way out 
except reducing the font size, but you already observed that ... :-)

Best,


André

Am 18.03.21 um 14:23 schrieb Alexis Poncet:
> Hi,
> 
> The following code fails with pyx.graph.axis.axis.NoValidPartitionError.
> 
> from pyx import *
> xaxis = graph.axis.log(min=10, max=1000)
> yaxis = graph.axis.log(min=1, max=100)
> g = graph.graphxy(width=1.2, x=xaxis, y=yaxis)
> g.writePDFfile()
> 
> I don't really understand why PyX is not able to find a partition. You 
> can check that the problem disappears with `width=1.3` or with 
> `unit.set(xscale=0.8)`.
> I solved by it by providing explicitely the ticks, but I feel that PyX 
> should be able to find a solution (as it does for the y axis).
> 
> ticks = [graph.axis.tick.tick(x, label=a) for x, a in zip([10, 100, 
> 1000], ["10", "", "1000"])]
> xaxis = graph.axis.log(min=10, max=1000, parter=None, manualticks=ticks)
> 
> I don't know if this qualifies as a bug, or if it is expected behavior.
> 
> Cheers,
> 
> Alexis
> 
> 
> 
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