Hi!

I would like to check the amount of trees measured with a DBH less than 20 cm in my survey for sample tree selection purposes. Is this possible in Collect?

Thanks!

asked 09 Oct '14, 20:52

Andras's gravatar image

Andras
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accept rate: 0%


Yes sure. Suppose that you have for example a biophisycal survey structured like cluster -> plot -> tree and you have an attribute "dbh" inside the "tree" entity, then you can select the trees that have a DBH greater than 20 with this expression: tree[dbh > 20].


Don't forget that the expressions will be evaluated considering the parent entity current schema node as "context", so the expression written before is valid if it's defined inside a attribute contained into the "plot" entity (the context will be "plot"). Instead, if you want to use it in an attribute defined inside the "tree" entity, the expression will become: parent()/tree[dbh > 20]. Thanks

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answered 09 Oct '14, 21:34

OF%20Collect's gravatar image

OF Collect ♦♦
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accept rate: 21%

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question asked: 09 Oct '14, 20:52

question was seen: 4,502 times

last updated: 09 Oct '14, 21:34