Scatter plots for a large dataset with 2 grouping variables

I have a large dataset with 4 variables. I want to make scatter plots for using two of the variables (x = date, y = d18O), GROUPED by the other two variables (site and depth). Specifically, I want there to be a single plot for each SITE, with different colored dataseries (x, y) based on DEPTH.

My code so far:

tT=readtable("data1.csv", "VariableNamingRule","preserve");
tT.Properties.VariableNames(2)={'Site'};    % shorten to be more convenient to use

G=grpstats(tT,{'Site','Depth'},{'mean','median','std'},'DataVars',{'Date','d18O'});

hSc=rowfun(@doit,tT,'GroupingVariables',{'Site'},'InputVariables',{'Date','d18O','Site','Depth'},'OutputFormat','uniform');

function h=doit(x,y,s,d)
  figure
  h=gscatter(x,y,d);
  xlabel('Date'),ylabel('d18O')
end

This code produces one graph that looks like what I want, but then I get an error :

Error using tabular/rowfun
The function 'doit' returned a non-scalar value when applied to the 1st group of rows.

Error in lysimeter_processing_code_v2 (line 6)
hSc=rowfun(@doit,tT,'GroupingVariables',{'Site'},'InputVariables',{'Date','d18O','Site','Depth'},'OutputFormat','uniform');

Any help appreciated!

*note attached dataset is only a tiny fraction of actual data, this code will be used for a very large dataset when I am done. (hence why I need to automate making the figures)

*in final dataset, each SITE will contain data for up to 4 DEPTHS

Answer 1

[Voss]

The function doit is written to return what gscatter returns, but gscatter returns an array of line handles - one line handle per group plotted - so doit returns a non-scalar array whenever there is more than one group plotted.

The solution is to make doit return a scalar no matter what. For instance, doit can return a scalar cell array containing the line handles returned from gscatter. (Or, if you don't need those line handles once the lines are created, you can just have doit return a scalar number, say 0 or 1 or NaN or anything else, or have doit return a status, say, logical true indicating it completed successfully.)

tT=readtable("data1.csv", "VariableNamingRule","preserve");
tT.Properties.VariableNames(2)={'Site'};    % shorten to be more convenient to use

G=grpstats(tT,{'Site','Depth'},{'mean','median','std'},'DataVars',{'Date','d18O'});

hSc=rowfun(@doit,tT,'GroupingVariables',{'Site'},'InputVariables',{'Date','d18O','Site','Depth'},'OutputFormat','uniform');

disp(hSc)

    {2×1 Line}
    {1×1 Line}
    {1×1 Line}
    {1×1 Line}
    {1×1 Line}

function out=doit(x,y,s,d)
  figure
  h=gscatter(x,y,d);
  out = {h}; % return a scalar cell array containing the lines
  xlabel('Date'),ylabel('d18O')
  title(sprintf('Site: %d',s(1))) % title the plot with the site value
end

[Emily]

thank you!

[Voss]

You're welcome!