BibTool Manual Reference Manual Semantic Checks Finding Double Entries

Finding Double Entries

When merging several bibliographic data bases a common problem is the occurrence of doubled entries in the resulting data base. When searching for double entries several problems arise. Which entries should be considered equal and what should happen to double entries.

The first question is answered as follows. Two entries are considered equal if their sort key is identical and they are adjacent in the final output. The first condition of identical sort keys allows the user to specify which criteria should be used when comparing entries. This can be achieved with the resource sort.format (see section Sorting). The second condition can easily be achieved by also sorting when requesting checking of doubles.

It remains the question what to do with the doubles. Usually it is not desirable to keep double entries in one data base, so only one entry found is kept. The others are printed as comments, i.e. the initial ``@'' is replaced by ``###''. Thus all information is still present but inactive in the BibTeX file. However, further processing with BibTool will remove these entries if pass.comments is off, which is the default.

Sometimes it is not desirable to include deleted entries in the output -- not even as comments. Then the default behaviour can be changed with the boolean resource print.deleted.entries. If this resource is off then deleted entries are suppressed completely.

The prefix for deleted entries is stored in the resource print.deleted.prefix which defaults to ``###''. Thus it can be redefined. However note that you should avoid using a string ending in an at sign @ since this would undo the effect of deleteing an entry.

The boolean resource check.double.delete can be used to delete double entries completely. For this purpose it has to be turned off as in:

check.double.delete = ON

The resource check.double can be used to turn on the checking of doubles. This feature is turned off initially.

check.double = ON

Checking of doubles can also be turned on with the command line option -d:

bibtool -d

BibTool Manual Reference Manual Semantic Checks Finding Double Entries