some modifications and updates

- change of imagesc to show nans as fully transparent
- new function istrunk

@GRIDobj/imagesc.m

@@ -4,28 +4,42 @@
 %
 % Syntax
 %
-% h = imagesc(DEM,varargin)
+% h = imagesc(DEM)
+% h = imagesc(DEM,'nanstransparent',true)
 %
 % Description
 %
-% see imagesc 
+% This function overloads the built-in imagesc. In contrast to imagesc,
+% however, the function sets nans in the DEM to transparent. For
+% further information see the documentation of imagesc. 
 %
+% 
 %
 % Author: Wolfgang Schwanghart (w.schwanghart[at]geo.uni-potsdam.de)
 % Date: 18. February, 2022
 
 %% Update on 18. Feb 2022
 % nans in the data are set to transparent
 
-[x,y] = refmat2XY(DEM.refmat,DEM.size);
-ht = imagesc(x,y,DEM.Z,varargin{:});
+p = inputParser;
+p.KeepUnmatched = true;
+addParameter(p,'nanstransparent',true, @(x) isscalar(x));
+parse(p,varargin{:})
 
+[x,y] = refmat2XY(DEM.refmat,DEM.size);
+ht = imagesc(x,y,DEM.Z,p.Unmatched);
 
 axis xy
 axis image
 
-ht.AlphaData = ~isnan(DEM.Z);
+if p.Results.nanstransparent
+ if isscalar(ht.AlphaData) 
+ ht.AlphaData = ~isnan(DEM.Z);
+ else
+ ht.AlphaData = ht.AlphaData .* (~isnan(DEM.Z));
+ end
+end
 
-if nargout == 1;
+if nargout == 1
  h = ht;
 end

@STREAMobj/istrunk.m

@@ -0,0 +1,29 @@
+function tf = istrunk(S)
+
+%ISTRUNK Determines whether STREAMobj consists of trunk streams
+%
+% Syntax
+%
+% tf = istrunk(S)
+%
+% Description
+%
+% istrunk determines whether a STREAMobj S consists of one or several
+% trunk streams. This is the case if there are as many outlet points as
+% there are channelheads.
+%
+% Input arguments
+%
+% S STREAMobj
+% 
+% Output arguments
+%
+% tf true or false
+%
+% See also: STREAMobj/streampoi
+%
+% Author: Wolfgang Schwanghart (w.schwanghart[at]geo.uni-potsdam.de)
+% Date: 21. February, 2022
+
+tf = numel(streampoi(S,'channelhead','ix')) == ...
+ numel(streampoi(S,'outlets','ix'));

readme.md

@@ -133,6 +133,7 @@ resource for code and examples is the [TopoToolbox blog](https://topotoolbox.word
 - modification: STREAMobj/smooth
 - new function: STREAMobj/mnoptimvar
 - modification: STREAMobj/STREAMobj2cell
+- modification: STREAMobj/istrunk
 - modification: GRIDobj/demprofile
 - new function: ScaleBar
 - new function: xlinerel and ylinerel