[R] calculate column means when missing data is present

[Luke Neraas]

# Hello,

# I have a matrix that contains some missing values denoted by NA.
# I would like to calculate the mean for each column and not have the
# NA values included.  here is a sample matrix  "X" below.


c1 <- c(1,4,3,2,NA,2,5,6,4,2)
c2 <- c(1,3,6,NA,NA,2,9,6,1,2)
c3 <- c(2,4,2,NA,4,2,NA,6,3,5)
c4 <- c(2,6,4,NA,4,2,NA,6,1,5)
c5 <- c(2,3,2,NA,4,2,9,6,NA,5)

X<-cbind(c1,c2,c3,c4,c5)

X

# I have tried a variety of methods to calculate the Column means but each time
# i do not get the result i am looking for

result<-colMeans(X)  # only returns a mean of NA


X <- X[!is.na(X)]    # Effectively removes the NA values but now I
cannot calculate Column Means

#  Below is the result of the column means I am looking for

result
       c1   c2    c3   c4    c5
 [1,] 3.22 3.75  3.5  3.75 4.125


# any help or ideas would be greatly appreciated

# thanks in advance

Luke Neraas

lukasneraas.r at gmail.com

University of Alaska Fairbanks
School of Fisheries and Ocean Sciences
11120 Glacier Highway
UAF Fisheries Division
Juneau, AK 99801