Chris Withers wrote:
> Eric Firing wrote:
>>> Specifically, what I have is an array like so:
>>>
>>> ['','','',1.1,2.2]
>>
>> Try something like this:
>>
>> import numpy.ma as ma
>> from pylab import *
>>
>> aa = [3.4, 2.5, '','','',1.1,2.2]
>> def to_num(arg):
>> if arg == '':
>> return 9999.0
>> return arg
>>
>> aanum = array([to_num(arg) for arg in aa])
>> aamasked = ma.masked_where(aanum==9999.0, aanum)
>> plot(aamasked)
>> show()
>
> What I ended up doing was getting my array to look like:
>
> from numpy import nan
> aa = [3.4,2.5,nan,nan,nan,1.1,2.2]
> values = numpy.array(aa)
> values = numpy.ma.masked_equal(values,nan)
This is not doing what you think it is, because any logical operation
with a Nan returns False:
In [4]:nan == nan
Out[4]:False
You should use numpy.masked_where(numpy.isnan(aa), aa).
In some places in mpl, nans are treated as missing values, but this is
not uniformly true, so it is better not to count on it.
Your values array is not actually getting masked at the nans:
In [7]:aa = array([1,nan,2])
In [8]:aa
Out[8]:array([ 1., NaN, 2.])
In [9]:values = ma.masked_equal(aa, nan)
In [10]:values
Out[10]:
masked_array(data = [1.0 nan 2.0],
mask = [False False False],
fill_value=1e+20)
Eric
>
> I only wish that masked_equal didn't blow up when aa contains datetime
> objects :-(
>
> cheers,
>
> Chris
>
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Matplotlib-users mailing list
Matplotlib-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/matplotlib-users
