Message-ID: <49F218AA.9020907@biostat.ku.dk>
Date: 2009-04-24T19:53:14Z
From: Peter Dalgaard
Subject: omit empty cells in crosstab?
In-Reply-To: <loom.20090424T194503-233@post.gmane.org>
Dieter Menne wrote:
> sjaffe <sjaffe <at> riskspan.com> writes:
>
>> I have data with many factors, each taking many values. However, only
>> relatively few combinations appear in the data, ie have nonzero counts, in
>> other words the resulting table is sparse. Say we have 10 factors each with
>> 10 levels. The result of table() would exceed the memory space (on a 32bit
>> machine). Is there any way to produce a table with empty cells omitted?
>> (without first producing the whole table and then removing rows.)
>
> It would be easier if you had a reproducible base example, but I
> suggest to create ONE new factor of the pasted levels using unique(),
> and creating a table of these.
interaction(..., drop=TRUE) may be a neater way.
--
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