Hi everybody,
Maybe this question is quite simple but i just don't know how to make it.
I have a matrix a somewhat like this one but bigger:
> a
f g h i j k
a NA NA 11 16 21 26
b NA NA 12 17 22 27
c NA 8 13 18 23 28
d NA 9 14 19 24 29
e NA 10 15 20 25 30
And i want to get the rows which at most have 2 Na.
Thanks in advance.
Shi Jiantao

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