Rewrite struct2json and cell2json

Author: robertoffmoura

plotly/plotly_aux/cell2json.m

@@ -1,10 +1,4 @@
 function str = cell2json(s)
-	str = '';
-	for i =1:length(s)
-		val = s{i};
-		valstr = m2json(val);
-		str = [str ', ' valstr];
-	end
-	str = str(3:end); % snip leading comma
-	str = ['[' str ']'];
-end
+	strList = string(cellfun(@m2json, s, un=0));
+	str = sprintf("[%s]", strjoin(strList, ", "));
+end

plotly/plotly_aux/struct2json.m

@@ -1,11 +1,5 @@
 function str = struct2json(s)
     f = fieldnames(s);
-    str = '';
-    for i = 1:length(fieldnames(s))
-        val = s.(f{i});
-        valstr = m2json(val);
-        str = [str '"' f{i} '"' ': ' valstr ', ' ];
-    end
-    str = str(1:(end-2)); % trim trailing comma
-    str = ['{' str '}']; 
+    strList = cellfun(@(x) sprintf('"%s" : %s', x, m2json(s.(x))), f, un=0);
+    str = sprintf("{%s}", strjoin(strList, ", "));
 end