omit empty cells in crosstab?
small example: a<-c(1.1, 2.1, 9.1) b<-cut(a,0:10) c<-data.frame(b,b) d<-table(c) dim(d) ##result: c(10, 10) But only 9 of the 100 cells are non-zero. If there were 10 columns, the table have 10 dimensions each of length 10, so have 10^10 elements, too much even to fit in memory
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. Dieter
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