So you want to skip the first column (comma delimited) and search for everything, where the second column is the same as the third column.
As a regex this can be written like this:
| | | | | | || └ Same match as what was captured
| | | | | | |└ Comma
| | | | | | └ End of captured group
| | | | | └ Any number of non-commas
| | | | └ Capture the following
| | | └ Start the match here
| | └ A comma
| └ Any number of non-commas
└ Start of line
You can use
:set hls to have a visual indication of what lines match the pattern.
Now if you want to delete those matching lines, you can simply use a
:g command, which basically means, do for all lines that match a certain pattern:
Or, if you already have the pattern in the search register (e.g. all matching lines are already colored), you can even simplify this call to:
Which means, delete all the lines that match the last entered search pattern.