matplotlib-users Mailing List for matplotlib

On Sunday 16 July 2006 19:38, Webb Sprague wrote:
> I have data with missing values represented by nans (like array([1.0,
> nan, 3.0]) that I am plotting with pylab.semilogy().

Please transform your array in a MaskedArray.
import numpy as N
masked_x=N.ma.masked_where(N.isnan(x),x)

That should do the trick.

Cf http://www.scipy.org/Cookbook/Matplotlib/Plotting_values_with_masked_arrays

I have data with missing values represented by nans (like array([1.0,
nan, 3.0]) that I am plotting with pylab.semilogy().  Unfortunately,
the lines are getting connected through the nans, while I was hoping
they would be left empty.  If someone could tell me how to get empty
lines, that would be great.

I get the behavior I expect with pylab.plot(), so if I need to I can
transform the data first, but I would rather get the log y-axis from
semilogy.

I am running version matplotlib 0.87.3 on Gentoo linux.

Thanks!

Works like a champ.

Thank you, S.

John Hunter wrote:
>>>>>> "Simon" == Simon Hook <sim...@jp...> writes:
>>>>>>             
>
>     Simon> Hi, [cross posted to egenix and matplotlib]
>
>     Simon> I have been using the egenix mxDateTime module and want to
>     Simon> plot some of the dates with Matplotlib (pylab). Pylab uses
>     Simon> num2date and date2num to covert datesandtimes to floating
>     Simon> point values for plotting.  Unfortunately if you give pylab
>     Simon> date2num an egenix DateTime object, pylab bombs. Is there a
>     Simon> simple way to use egenix DateTime objects with Pylab?
>
> See matplotlib.dates.mx2num
>
> JDH
>   

Simon Hook wrote:
> Hi,
> 
> [cross posted to egenix and matplotlib]
> 
> I have been using the egenix mxDateTime module and want to plot some of
> the dates with Matplotlib (pylab). Pylab uses num2date and date2num to
> covert datesandtimes to floating point values for plotting.
> Unfortunately if you give pylab date2num an egenix DateTime object,
> pylab bombs. Is there a simple way to use egenix DateTime objects with
> Pylab?
> 
> Below is a simple example
> 
> #D:\apps\Python23\python.exe
> 
> from datetime import *
> from mx.DateTime import *
> from pylab import *
> 
> # This works
> a=datetime(2005,10,10,5,5,5)
> print a
> 
> # This works
> b=DateTime(2005,10,10,5,5,5)
> print b
> 
> # This works
> c=date2num(a)
> print c
> 
> # This fails
> d=date2num(b)
> print d
> 
> The output and failure message is:
> 
> 2005-10-10 05:05:05
> 2005-10-10 05:05:05.00
> 732229.211863

I'm not sure what date2num() uses as epoch, but it looks like
some variant of a Julian Day Number:

>>> b.jdn
2453653.711863426
>>> b.tjd
3653.2118634259259

> Traceback (most recent call last):
>  File "datetime-problem.py", line 20, in ?
>    d=date2num(b)
>  File "D:\apps\Python23\lib\site-packages\matplotlib\dates.py", line
> 174, in da
> te2num
>    if not iterable(d): return _to_ordinalf(d)
>  File "D:\apps\Python23\lib\site-packages\matplotlib\dates.py", line
> 137, in _t
> o_ordinalf
>    base =  dt.toordinal()
> AttributeError: toordinal

.toordinal() is a datetime method which is not supported by mxDateTime
instances.

-- 
Marc-Andre Lemburg
eGenix.com

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________________________________________________________________________

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>>>>> "Simon" == Simon Hook <sim...@jp...> writes:

    Simon> Hi, [cross posted to egenix and matplotlib]

    Simon> I have been using the egenix mxDateTime module and want to
    Simon> plot some of the dates with Matplotlib (pylab). Pylab uses
    Simon> num2date and date2num to covert datesandtimes to floating
    Simon> point values for plotting.  Unfortunately if you give pylab
    Simon> date2num an egenix DateTime object, pylab bombs. Is there a
    Simon> simple way to use egenix DateTime objects with Pylab?

See matplotlib.dates.mx2num

JDH

Hi,

[cross posted to egenix and matplotlib]

I have been using the egenix mxDateTime module and want to plot some of 
the dates with Matplotlib (pylab). Pylab uses num2date and date2num to 
covert datesandtimes to floating point values for plotting. 
Unfortunately if you give pylab date2num an egenix DateTime object, 
pylab bombs. Is there a simple way to use egenix DateTime objects with 
Pylab?

Below is a simple example

#D:\apps\Python23\python.exe

from datetime import *
from mx.DateTime import *
from pylab import *

# This works
a=datetime(2005,10,10,5,5,5)
print a

# This works
b=DateTime(2005,10,10,5,5,5)
print b

# This works
c=date2num(a)
print c

# This fails
d=date2num(b)
print d

The output and failure message is:

2005-10-10 05:05:05
2005-10-10 05:05:05.00
732229.211863
Traceback (most recent call last):
  File "datetime-problem.py", line 20, in ?
    d=date2num(b)
  File "D:\apps\Python23\lib\site-packages\matplotlib\dates.py", line 
174, in da
te2num
    if not iterable(d): return _to_ordinalf(d)
  File "D:\apps\Python23\lib\site-packages\matplotlib\dates.py", line 
137, in _t
o_ordinalf
    base =  dt.toordinal()
AttributeError: toordinal


thanks, Simon