How can I allocate the $rownum value in reverse order in QGIS?
I have a created a grid layer to use in an atlas and the ID allocated is from top left to bottom right - which is what I want if I want to create a $rownum attribute to use as the map number in my atlas (e.g. 1 - 78)
But I have selected only those grid polygons that have relevant data beneath them for my maps, so I have created a grid layer that is a subset of the original. In this subset grid, the ID numbers have been reversed - that is, they go from bottom right to top left so if I create the $rownum field the numbers will be in that reverse [new] order. (e.g. 45 - 1).
So I want to allocate that $rownum attribute in reverse order so that the atlas maps read from top left to bottom right.
Can anyone help?