[R] empty cells in ftable

[temiz]

hello

when I enter:
ftable(xtabs(cnt~jeo+slp+pcurv+asp+hey),data=dt)

it gives a frequncy table. But some cells are empty.
like this:

19            2           72      0
                3           68      0
                4           99      0
                5          110      0
                6           97      0
                7           74      0
                8           46      0
.
.
.


(Those empty cells must have previous non empty values.)

how can I get a table  that  does not contain empty  cells ?

Is this the proper table that will be used in logistic regression ?

regards

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