On Mon, Jul 5, 2010 at 11:26 PM, Craig DeForest <[email protected]> wrote: > Hi, Puneet, > > BAD value marking is in-band. That means you have to specify one of the > possible values for your storage class that will be the BAD value. For > example, if you are storing unsigned bytes (PDL class "byte"), you could > make 255 the BAD value, with valid data points having values between 0 and > 254. If that doesn't work for you, you must upgrade to a larger storage > class (e.g. ushort) so that you can make the BAD value be out of the range > of valid values for your data (using the "badvalue" method). > > One way to create your PDL full of BAD is: > $data = PDL->new_from_specification(byte, $size); > $data->badflag(1); > $data->badvalue(pdl(byte, 255)); > $data .= 255; > >
Thanks Craig. That should set me off on my quest. > > > On Jul 5, 2010, at 10:08 PM, P Kishor wrote: > >> This is in support of an earlier question I had asked -- imagine I >> have a byte piddle $a with, say, 1000 elements. I don't have all the >> values yet that will go into the piddle -- I am going to get the >> values for different positions in the piddle at different times. So, I >> get $a->at(3) today, and $a->at(549) tomorrow and so on. All >> legitimate values fall between 0 and 255 inclusive, or could also be >> null values. How do I start putting together my piddle so that when I >> have all the values, I have a well-formed piddle with all the values >> in correct order? >> >> I could create a fake 1000 element piddle, and then, set the correct >> values when I get them. However, I can't create my fake piddle with >> any number between 0 and 255, nor can I use a null value. If I use a >> value above 255, or use something like -999, then it won't be a byte >> piddle. >> >> So, I thought, I could exploit BAD values. I could create a 1000 >> element piddle filled with BAD values, and then, as I get the real >> values, turn those positions in the piddle on to the correct values. >> >> Is this a reasonable strategy? If yes, how do I create a byte piddle >> filled with BAD values? Do I use setbadat? >> >> >> -- >> Puneet Kishor >> >> _______________________________________________ >> Perldl mailing list >> [email protected] >> http://mailman.jach.hawaii.edu/mailman/listinfo/perldl >> > > -- Puneet Kishor http://www.punkish.org Carbon Model http://carbonmodel.org Charter Member, Open Source Geospatial Foundation http://www.osgeo.org Science Commons Fellow, http://sciencecommons.org/about/whoweare/kishor Nelson Institute, UW-Madison http://www.nelson.wisc.edu ----------------------------------------------------------------------- Assertions are politics; backing up assertions with evidence is science ======================================================================= _______________________________________________ Perldl mailing list [email protected] http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
