[R-SIG-Finance] Testing existence in xts

[Worik Stanton]

How do I test for the existence of an entry in a xts?

Given xts z
> z
              z
2009-01-08 1.71
2009-01-09 1.72
2009-01-12 1.71

and I want to test if z["2009-01-10",] exists, how do I do it?

cheers
Worik
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