When using the 'DisplayName' property when plotting (e.g: plot(x, y, 'DisplayName', 'Sofia')), legendUnq() will search for unique 'DisplayName' strings within a vector of figure or axis handles and removes duplicate values. This cleans up the legend when plotting in a loop or when the the same data appear more than once in a figure. This also makes it easy to use one legend across several subplots within a figure. Plot elements with an empty 'DisplayName' will not be included in the legend so you won't have any of those generic 'Data1' items.
unqHandles = legendUnq(h) searches all data in the figure or axis handle 'h' (h can also be a vector of axis handles) that has a 'DisplayName' string used by legend(). Duplicate DisplayName strings are removed. Call legend(unqHandles) to produce the legend showing unique components. If a plotted object does not have a DisplayName, it will not appear in the legend.
Common problems this solves:
1) Removes duplicates in a legend
2) Removes legend elements that weren't intended to be in the legend (i.e., that have empty 'DisplayName')
3) Makes it easy to have 1 legend that covers all subplots in a figure.
1) fixed error when plot is empty