Problem 73. Replace NaNs with the number that appears to its left in the row.

Created by Cody Team

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Replace NaNs with the number that appears to its left in the row.

If there are more than one consecutive NaNs, they should all be replaced by the first non-NaN value to the immediate left of the left-most NaN. If the NaN is in the first column, default to zero.

For example, if

x = [NaN  1   2  NaN NaN 17  3  -4 NaN]

then

y = [ 0   1   2   2   2  17  3  -4  -4]

Solve

Solution Stats

4390 Solutions
1778 Solvers

Last Solution submitted on Apr 06, 2020

Last 200 Solutions

Problem Comments

1 Comment

1 Comment

Richard Zapor on 29 Apr 2012

The problem does not limit the array to a single row. Add a few cases of multiple rows or define as single row.

Solution Comments

Solution 2177485

1 Comment

1 Comment

Álmos Laza on 27 Mar 2020 at 7:18

x = [1:10 NaN];
y_correct = [ 1:10 10];
assert(isequal(replace_nans(x),y_correct))
c =

1 2 3 4 5 6 7 8 9 10 NaN
Output argument "y" (and maybe others) not assigned during call to "replace_nans".

Error in Test4 (line 3)
assert(isequal(replace_nans(x),y_correct))

why wont this pass?

Solution 694859

2 Comments

2 Comments

Mark Matusevich on 1 Jul 2015

Not really a solution, more like a "white flag" regarding this direction.

Sanzhar Askaruly on 17 Jun 2019

hint: recursion

Solution 501949

1 Comment

1 Comment

Vishal on 16 Sep 2014

big size ...!

Solution 341836

3 Comments

3 Comments

Pavan Toraty on 29 Oct 2013

I just realized that you can cause inconvenience to some players by posting cody problems like "Hello Everyone!!!". I did create that cody problem just to say Hi to my fellow cody players. It was not intended to waste your time or cause inconvenience. My apologies for whoever deleted that problem.

Alfonso Nieto-Castanon on 29 Oct 2013

I am sure it was deleted by mistake, there are plenty of similar Cody problems (think Chuck Norris, indian mathematicians, smartest matlab programmers, and a long etc...) Perhaps Ned can put it back up?

Pavan Toraty on 30 Oct 2013

Thanks for the reply sir.

Solution 156396

2 Comments

2 Comments

Rody Oldenhuis on 1 Nov 2012

Strange...those assertions pass on my computer

Dennis J on 10 Jul 2013

For the second test it gives: [0 0 1 2 2 2 17 3 -4] instead of [0 1 2 2 2 17 3 -4 -4]

Solution 152140

1 Comment

1 Comment

Dennis J on 10 Jul 2013

Nice, it is very intuitive that a solution with this function is possible but still hard to find.

Solution 10987

2 Comments

2 Comments

Christopher on 26 Apr 2012

It's like a lesson. logical indices don't have to be full size! And for will apparently loop through a vector! Thanks!

Christopher on 26 Apr 2012

Bonus! Vector doesn't have to be monotonic!

Problem Recent Solvers1778

Problem Tags

matlab