MATLAB Answers

0

How do I exclude NaN values when calculating mean of each row in a matrix?

Asked by Jillian Sweatt on 8 Sep 2017
Latest activity Answered by Changoleon on 5 Mar 2018
gpd=[2014,3.320,3.364,3.532,3.659,3.691,3.695,3.633,3.481,3.403,...
3.182,2.887,2.560;2015,2.110,2.249,2.483,2.485,2.775,2.832,...
2.832,2.679,2.394,2.289,2.185,2.060;2016,1.967,1.767,1.958,...
2.134,2.264,2.363,2.225,2.155,2.208,2.243,2.187,2.230;2017,...
2.351,2.299,2.323,2.418,2.386,2.337,2.281,NaN,NaN,NaN,NaN,NaN];
for a=gpd(:,end)
y=mean(a,2);
end
The output for the last row of y returns NaN (a copy of the command window is shown below). How do you exclude the NaN values in the last row in order to output an average of all the real number values?
>>y =
2.5600
2.0600
2.2300
NaN

  0 Comments

Sign in to comment.

Tags

Products

4 Answers

Answer by Guillaume
on 8 Sep 2017

Since version 2015a, the max, min, mean, median, sum, var, std, and cov function have included a flag to ignore nans
y = mean(gpd, 2, 'omitnan')
Note that your loop makes no sense at all. It's averaging just the last column, so not doing any averaging at all. The line above will average all the columns.

  0 Comments

Sign in to comment.


Answer by José-Luis
on 8 Sep 2017

y = nanmean(a,2)

  0 Comments

Sign in to comment.


Answer by OCDER
on 8 Sep 2017
Edited by OCDER
on 8 Sep 2017

Remove the for loop, as it only does the last column, which can't be averaged.
To take mean with NaN's in it, use José-Luis' suggestion of nanmean (voted your answer up :) ).
y = nanmean(gpd, 2)
This will return a 5x1 matrix of average of gdp for each row.
y =
158.0313
157.2595
157.0539
254.1744

  2 Comments

Will that still calculate the mean of the remaining numbers in the last row of gpd?
Actually, I'm looking at your code and this for loop may not be needed:
for a = gpd(:, end)
... %This only does one iteration, where a = last column.
end
In this case, José-Luis' suggestion of nanmean is correct.

Sign in to comment.


Answer by Changoleon on 5 Mar 2018

https://www.mathworks.com/help/stats/nanmean.html

  0 Comments

Sign in to comment.