Re: ListDensityPlot with irregular data and InterpolationOrder
- To: mathgroup at smc.vnet.net
- Subject: [mg88584] Re: ListDensityPlot with irregular data and InterpolationOrder
- From: Szabolcs Horvát <szhorvat at gmail.com>
- Date: Fri, 9 May 2008 03:23:55 -0400 (EDT)
- Organization: University of Bergen
- References: <fvudo3$ec7$1@smc.vnet.net>
Bill Rowe wrote:
> On 5/7/08 at 7:10 AM, szhorvat at gmail.com (Szabolcs Horv=C3=A1t) wrote:
>
>> This is not explicitly documented (or at least I could not find any
>> mention of it), but from looking at the plots it seems to me that
>> with ListDensityPlot (and related functions), an InterpolationOrder
>> higher than 1 only work with data that lies on a regular grid.
>
>> So for example the following data cannot be plotted with
>> InterpolationOrder higher than 1:
>
>> data = {#1, #2, Sin[#1] Sin[#2]} & @@@ RandomReal[2 Pi, {100, 2}];
>
>> Is this correct?
>
> The array you create above is a regular array and as far as I
> can see there is no problem with using an InterpolationOrder
> greater than 1. That is, using your code above to assign values
> to data
>
>
> ListDensityPlot[data]
> ListDensityPlot[data,InterpolationOrder->1]
> ListDensityPlot[data,InterpolationOrder->3]
>
> all execute with no error messages.
>
> True, all three graphics appear identical. But I believe this is
> due the functional relationship you created.
>
> Do the following
>
> data=RandomReal[2 Pi, {5,5}];
>
> then
>
> ListDensityPlot[data]
> ListDensityPlot[data,InterpolationOrder->1]
> ListDensityPlot[data,InterpolationOrder->3]
>
> All three should execute with no error and the images will not
> be the same due to the different interpolation order.
Exactly this is what I mean, i.e. that when passing arbitrary data
points to ListDensityPlot (instead of data on a regular grid),
InterpolationOrder seems to only have an effect if we use
InterpolationOrder -> 0. Otherwise the result will be the same as with
InterpolationOrder -> None.
So it seems that ListDensityPlot can only interpolate on a grid, but not
in a more general situation.
This is not a problem, of course, but I got a bit confused because it
gives no error message!