Problem 58339. Remove runs of at least n consecutive NaNs

Christian Schröder

5 solvers

0 likes

Solve

Solve Later

This problem is inspired by Dyuman Joshi's problem 58329. Given a row vector x and a natural number n, remove all runs of at least n consecutive NaNs from x, leaving all shorter runs as well as all non-NaN elements intact.
For instance, given
x = [1 NaN 2 3 NaN NaN 4 5 6 NaN NaN NaN 7 8 9 10 NaN NaN NaN NaN]
the results would be as follows:
>> removenans1n(x, 1)
ans =
     1     2     3     4     5     6     7     8     9    10
>> removenans1n(x, 2)
ans =
     1   NaN     2     3     4     5     6     7     8     9    10
>> removenans1n(x, 3)
ans =
     1   NaN     2     3   NaN   NaN     4     5     6     7     8     9    10
>> removenans1n(x, 4)
ans =
     1   NaN     2     3   NaN   NaN     4     5     6   NaN   NaN   NaN     7     8     9    10
>> removenans1n(x, 5)
ans =
     1   NaN     2     3   NaN   NaN     4     5     6   NaN   NaN   NaN     7     8     9    10   NaN   NaN   NaN   NaN
with no changes in output for even higher n (since x only contains runs of NaNs up to length four).
To make this challenging, provide a vectorized solution: no loops, no arrayfun (in fact, no fun at all, though you're still allowed to have fun), and no recursion. Regular expressions are also outlawed (I don't think that this is a problem that is naturally solved using regular expressions, so I don't feel too bad about doing so). 