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I often come across GBIF users who are unaware that the available records for a given taxon are not necessarily all presences: there is a column called “Occurrence” which can have a value of “Present” or “Absent”. Is! Absence records can, of course, be removed with simple operations in R or even omitted from downloads, but many users overlook or accidentally skip this important step, and Then analyze the distribution of species with some absence records used as presence.
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To reduce the likelihood of this happening, I added new arguments to the fuzzysim function cleanRecords() (which was explained in a previous post) to allow absence records to be removed as well, when the user only wants to filter out presentations. . Here is an example of using aardvark occurrence records downloaded with the geodata package. Note that this requires the latest version of Fujisim (4.9.9) to be installed:
occ
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As you can see, in addition to some common biodiversity data issues such as duplicate or incorrect coordinates, additional records were removed because they represented absences. Hopefully this can help prevent their mis-use as species exist. Feedback is welcome!
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