Any way to populate a grid from input vectors?

albrightand · March 1, 2023, 9:52pm

Is there any existing package to take two input vectors and create a grid (similar to meshgrid) and then output a raster based on a third dimension? Something that recreates roundgridfun.m in Matlab.

github.com

hokiespurs/general-purpose-matlab/blob/master/gridding/roundgridfun/roundgridfun.m

function [val,numpts]=roundgridfun(varargin)
% ROUNDGRIDFUN grids data using a nearest neighbor gridding technique
%   This function is a very simplistic gridding function which effectively
%   bins the data to find the nearest grid node, then performs the input
%   function on all of the points for each node.
%
%   The grid nodes must be evenly spaced in each dimension.
%
%   The function works for ND datasets (tested up to 5D)
%
%   1D: [val,numpts]=roundgridfun(x,y,xg,@fun);           % Vector
%   2D: [val,numpts]=roundgridfun(x,y,z,xg,yg,@fun);      % Surface
%   3D: [val,numpts]=roundgridfun(x,y,z,I,xg,yg,zg,@fun); % Voxels
%
%   The common input functions are @mean, @min, @max, @std, @var
%   The function handle @(x) {x} can be used to return a cell array with
%   all of the data in each grid node bin
%
% Inputs:
%    - x : nx1 : vector of x values

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joa-quim · March 1, 2023, 11:03pm

Well, GMT.jl has these guys (all 2D gridders)

stevengj · March 2, 2023, 1:43am

If you google “meshgrid Julia”, this comes up as the first link: Meshgrid function in Julia

TLDR: yes, there are plenty of examples of meshgrid routines in Julia, e.g. here or better yet LazyGrids.jl, but people generally learn to use broadcasting instead.

albrightand · March 2, 2023, 3:42pm

joa-quim,

I think the bin gridders function is what I’m looking for. I was hoping GMT would already have some kind of function for that. Thanks for the assist. I’ll post my code once I figure how to get it working.