Jay de Halas wrote:
> More to the point, I am having an issue using "Filter: Expression" with
> Date type Data. The Filter: Expression tool works great with numerical
> data, but it appears to be unable to perform Boolean operations with Date
> type data.
> With Date type data the Boolean expression appears to evaluate, but
> generates zero length data sets for the result data.
THis is a shortcoming with the current filtering plugin, as it uses Python
to evaluate the expression and it assumes numerical datasets.
However, there is a hacky workaround (which might not be supported in future
versions).
If you go to the Edit->Custom Definitions menu item. Click Add to get a new
item, change the Type to "import", Name to "veusz.utils" and Definition to
"dateStringToDate". You'll get some warnings as you do this - click Allow or
Allow Always here - I need to get rid of these when you are using this
dialog.
Now you should be able to do filter expressions like
mydataset > dateStringToDate('2011-01-01') & mydataset <
dateStringToDate('2012-01-01T01:02:03')
Unfortunately the type of the output dataset will be wrong, but you can
still plot it as a date.
I should fix Veusz to have a function like this as standard (maybe
Date('2011-01-01')) and keep the datatype the same after filtering.
Jeremy
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