Thread: [Matplotlib-users] problem with small y-axis scale

I get strange "histogram-like" plots if the y-axes scale is some orders 
of magnitude smaller than the x-axis (latest svn version).

In [43]: matplotlib.__version__
Out[43]: '0.88svn'

# bad
x = arange(0,10,.1); y = sin(x)/100.0; plot(x,y); savefig('small_y.eps')

# good
x = arange(0,10,.1); y = sin(x); plot(x,y); savefig('normal_y.eps')

This doesn't happen if I export as .png

-- 
Random number generation is the art of producing pure gibberish as 
quickly as possible.

>>>>> "Steve" == Steve Schmerler <el...@gm...> writes:

    Steve> I get strange "histogram-like" plots if the y-axes scale is
    Steve> some orders of magnitude smaller than the x-axis (latest
    Steve> svn version).

This appears to be a truncation error due to the formating string we
use to represent floats in backend_ps.  Darren, should we prefer 1.3e
instead of 1.3f, or perhaps 1.4e or 1.5e?

JDH

John Hunter wrote:
>>>>>>"Steve" == Steve Schmerler <el...@gm...> writes:
> 
> 
>     Steve> I get strange "histogram-like" plots if the y-axes scale is
>     Steve> some orders of magnitude smaller than the x-axis (latest
>     Steve> svn version).
> 
> This appears to be a truncation error due to the formating string we
> use to represent floats in backend_ps.  Darren, should we prefer 1.3e
> instead of 1.3f, or perhaps 1.4e or 1.5e?

John, Darren,

I would suggest something like 1.5g, which will be less bulky for common 
cases than 1.5f.

Matlab ps files have all paths already transformed to paper coordinates 
but in very small units (thousandths of an inch?) so that they can be 
given as integers.

Eric

John Hunter wrote:
>>>>>>"Steve" == Steve Schmerler <el...@gm...> writes:
> 
> 
>     Steve> I get strange "histogram-like" plots if the y-axes scale is
>     Steve> some orders of magnitude smaller than the x-axis (latest
>     Steve> svn version).
> 
> This appears to be a truncation error due to the formating string we
> use to represent floats in backend_ps.  Darren, should we prefer 1.3e
> instead of 1.3f, or perhaps 1.4e or 1.5e?
> 

Replacing %f by %e and %1.3f by %1.5e in the latest svn version's 
backend_ps.py solves the problem.

cheers,
steve

-- 
Random number generation is the art of producing pure gibberish as 
quickly as possible.

I think 1.4g is the way to go. It's fixed in svn 2252.

On Sunday 02 April 2006 22:55, John Hunter wrote:
> >>>>> "Steve" == Steve Schmerler <el...@gm...> writes:
>
>     Steve> I get strange "histogram-like" plots if the y-axes scale is
>     Steve> some orders of magnitude smaller than the x-axis (latest
>     Steve> svn version).
>
> This appears to be a truncation error due to the formating string we
> use to represent floats in backend_ps.  Darren, should we prefer 1.3e
> instead of 1.3f, or perhaps 1.4e or 1.5e?
>
> JDH
>
>
>
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Darren S. Dale, Ph.D.
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