CODEWITHSUNDEEP
rmedian
Ramon_88
Ramon_88

Reputation: 109

problem with missing values for calculating the median

I'm having problem with managing with NAs to calculate median by using multiple matrix.

This is an example of the code and data I'm working on:

#Data example

m1 = matrix(c(2, 4, 3, 1),nrow=2, ncol=2, byrow = TRUE)  
m2 = matrix(c(NA, 5, 7, 9),nrow=2, ncol=2, byrow = TRUE)
m3 = matrix(c(NA, 8, 10, 14),nrow=2, ncol=2, byrow = TRUE)
 
Median calculation

apply(abind::abind(m1, m2, m3, along = 3), 1:2, median)
         [,1] [,2]
     [1,] NA    5
     [2,]  7    9

As expected the the function doesn't return a value for cells which contains NAs.

The problem is that if I replace NAs with 0 I'll get an output like this:

#Data example

m1 = matrix(c(2, 4, 3, 1),nrow=2, ncol=2, byrow = TRUE)  
m2 = matrix(c(0, 5, 7, 9),nrow=2, ncol=2, byrow = TRUE)
m3 = matrix(c(0, 8, 10, 14),nrow=2, ncol=2, byrow = TRUE)
 
Median calculation

apply(abind::abind(m1, m2, m3, along = 3), 1:2, median)
         [,1] [,2]
     [1,]  0    5
     [2,]  7    9

I'm trying instead to get an output where cells which reports NAs are just skipped so that only values are take into consideration. As in the example, if I have cells with NA, NA, 2 I would expect to get 2 as result while (out of the example) for cells with NA,2,5 I would expect 3.5 as result.

         [,1] [,2]
     [1,]  2    5
     [2,]  7    9

Do you have an idea of how I could get this results? Any suggestion would be appreciated, thanks.

Upvotes: 0

Views: 130

Answers (2)

Kensho
Kensho

Reputation: 57

Perhaps you should drop de NA's first? Try adding na.rm = TRUE

Upvotes: 1

Panagiotis Togias
Panagiotis Togias

Reputation: 323

Just pass the argument na.rm=TRUE inside apply

apply(abind::abind(m1, m2, m3, along = 3), 1:2, median, na.rm = TRUE)

Output:

     [,1] [,2]
[1,]    2    5
[2,]    7    9

Upvotes: 1

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