Input
[ 1 NaN 5 NaN 2
2 NaN 4 4 8
6 NaN 8 2 4
0 0 0 0]
should return 3 because last NaN is observed in third row.
Test suite may be changed!
there seem to be some problems with the testsuite, in particular some of those matrices contain different number of elements per row (e.g. perhaps "5,7" should be "5.7"). I guess the same applies to your example dataset where the last row contains only four numbers instead of five?
I have fixed test suite.
The test sets 2,3,5, and 6 have a problem with x. It should probably read 5.7 and not 5,7
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