>I have some 2-D data, and want to use the data and it's location at the
>same time, so I use Extract to get the "positions", then use "Compute" to
>do the calculation, but I got the message that the structure of inputs of
>Compute don't match. What's the problem? Thank you so much.
>
>yuzhong
I should first say that I have both a full-time job at Cornell doing
visualization consulting and run a DX consulting company (which is also
nearly full-time) to be able to offer my expertise to non-Cornell
interests, and I'm real busy right now. I'm happy to answer questions on
the list when I get a chance, but for the good of all reading, not any one
individual. For individual consulting in any depth, I charge. There are
others who monitor the users list that also answer questions when I'm too
busy (frequently). Just saying this before we get into a spiral here. (My
company also offers prepaid email tech support on an annual basis, if MS
State is interested). (I'm not busting on you personally, Yuzhong, just
making my position clear to the list at large, though I note that you sent
this mail to me personally; I have a hunch you are about to send me a lot
more email and I want to head that off).
I do hope you've had a chance to read the extensive documentation that
comes with OpenDX, though I admit that beginners can't necessarily "get" it
from reading the docs. There are also extensive samples to study.
You also need to provide more detail in your questions. While I'm a big fan
of parsimonious emails (versus those who copy the whole huge entire thread
that's gone before in a discussion group), your email questions border on
the austere. I think you'll get more help if you post a tiny bit of example
data for your current problem so we can see just what you are trying to do.
I can't figure out if you've imported it in an inappropriate way thus
making the problem harder to solve, or if you are manipulating it in a
clever way, which DX does in fact support. But your questions reveal that
you don't fully understand the object structure of DX yet and that is
critical to making headway.
So to try to answer the question:
Extract rips out a bare array (component) from a field.
BUT, most DX modules require a field (or group) structure. You can't feed
them a bare array.
DX fields fundamentally require a "positions" component even if there are
no other components present. To have "data" you must first have
"positions". To have interpolation you must also have "connections". So,
most common fields have 3 components at least.
You do NOT have to remove data from a field to Compute on it. If you want
to work on the "positions" using Compute, you Mark("positions"), Compute on
this new "data", then Unmark("positions"), assuming you wanted to modify
the positions values of the field while leaving the original data unchanged.
If you want to in effect "copy" the positions into the "data" component,
just don't do the Unmark. The field that comes out of Compute will have the
original positions, and the Marked/Computed "data" which was a copy of
positions before you Computed on it.
Use Print("rd") a LOT while learning DX and this will all make sense. Just
hook up Print to the output of each module and study the output. Note that
you can Clear the Message Window which helps see only the results of the
current execution more easily (File menu in Message Window).
Cheers,
Chris Pelkie
Vice President/Scientific Visualization Producer
Conceptual Reality Presentations, Inc.
30 West Meadow Drive
Ithaca, NY 14850
[EMAIL PROTECTED]
(607) 257-8335 or (607) 254-8794
