[R] Finding Source of Error Message of 'Non-Unique Index Entries'

[Rich Shepard]

On Tue, 3 Jan 2012, David Winsemius wrote:

> burns.tds[ !duplicated(burns.tds) ,  ]

   Apparently it does not matter if the site column in the data frame is a
factor or a character, read.zoo() generates the same error. Applying the
above produces a long list starting with:

burns.tds[!duplicated(burns.tds), ]
         site   sampdate    quant
599     BC-3 1992-03-27    0.100
600     BC-3 1992-04-30    0.100
601     BC-3 1992-05-30    0.100
603     BC-3 1992-06-19    0.100
1214    BC-3 1992-07-20    0.100
1215    BC-3 1992-08-10    0.100
1216    BC-3 1992-09-30    0.100
1217    BC-3 1992-10-29    0.100
1218    BC-3 1992-11-19    0.100
1929    BC-3 1995-03-23    8.080

   I don't know how to interpret this. I don't see two rows with the same
values, but ~ 500 rows each with a different value. What is duplicated? The
entire row? The site ID?

   ?duplicated has some examples, but those do not show the output of the
function nor explain what's duplicated.

   I need to get past this blockage and appreciate your help in determining
why read.zoo() sees duplicates when the database table has none, and how to
resolve this issue.

TIA,

Rich