[R] Finding Missing Data Patterns

[Uwe Ligges]

Wolfgang Viechtbauer wrote:
> 
> Dear R-Helpers,
> 
> I have a large data matrix, which contains missing data. The matrix
> looks something like this:
> 
> 1) X  X  X  X  X  X NA NA NA
> 2) NA NA NA NA X  X  X  X  X
> 3) NA NA X  X  X  X NA NA NA
> 4) X  X  X  X  X  X  X  X  X
> 5) X  X  NA NA X NA NA NA NA
> 
> and so on. Notice that the first row starts with complete data but ends
> with missing. The second row starts with missing, but the rest is
> complete. The third starts and ends with missing, but the middle part is
> complete. The fourth is complete. What I want to do is filter out
> patterns like in row 5, where the data are interrupted by missing data.
> Basically, I need to test each row for a "data, at least one NA, data"
> pattern.
> 
> Is there some kind of way of doing this? I am at a loss for an easy way
> to accomplishing this. Any suggestions would be most appreciated!
> 
> --
> Wolfgang Viechtbauer

Presumably not most efficient, but it came into my mind at first:

  apply(X, 1, function(x) grep("0.1.0", paste(as.numeric(is.na(x)),
collapse="")))

Uwe Ligges