I want to group and count features with the same code attribute value.
I can classify the data and enable feature count in the layer list but I cannot get counts in the attribute table.
This was the best result on Google I could find, but the screenshot tutorial by G M is out of date and it took me a while to work out how to use the plugin.
How this helps other people.
I suggest you to install Group Stats plugin. Here is a quick tutorial:
The Count will appear. If you go to preferences you should be able to select only Count avoiding the other parameters to be displayed (this is not my case...). Remember before click Save button you have to select the fields you want to add to your .csv: hold on Shift for do that. Here is a more advanced tutorial written by Anita Graser.