# [R] replace Na values with the mean of the column which contains them

arun smartpink111 at yahoo.com
Mon Jul 29 19:57:49 CEST 2013

```Hi,

de<- structure(c(NA, NA, NA, NA, NA, NA, NA, NA, 0.27500571, -3.07568579,
-0.42240954, -0.26901731, 0.01766284, -0.8099958, 0.20805934,
0.03036708, -0.26928087, 1.20925752, 0.38012008, -0.41778861,
-0.49677462, -0.13248754, -0.54179054, 0.35788624, -0.41467591,
-0.59234248, 0.73642396, -0.06768044, -0.40321968, -1.52283305,
0.25974308, -0.0401373, -0.1192078, 0.9325334, -1.8927164, 1.4330507,
0.2892706, 1.3976522, 0.2295291, -0.5009389, -0.342656, -0.8439027,
-0.4971999, -1.6127122, -0.6508823, 1.4729576, -1.6093478, 0.1686006
), .Dim = c(16L, 3L))

sapply(seq_len(ncol(de)),function(i) {de[,i][is.na(de[,i])]<-mean(de[,i],na.rm=TRUE);de[,i]})
A.K.

Hi everyone

I have a problem with replacing the NA values with the mean of
the column which contains them. If I replace Na with the means of the
rest values in the column, the mean of the whole column will be still
the same as if I would have omitted NA values. I have the following data

de
[,1]        [,2]       [,3]
[1,]          NA -0.26928087 -0.1192078
[2,]          NA  1.20925752  0.9325334
[3,]          NA  0.38012008 -1.8927164
[4,]          NA -0.41778861  1.4330507
[5,]          NA -0.49677462  0.2892706
[6,]          NA -0.13248754  1.3976522
[7,]          NA -0.54179054  0.2295291
[8,]          NA  0.35788624 -0.5009389
[9,]  0.27500571 -0.41467591 -0.3426560
[10,] -3.07568579 -0.59234248 -0.8439027
[11,] -0.42240954  0.73642396 -0.4971999
[12,] -0.26901731 -0.06768044 -1.6127122
[13,]  0.01766284 -0.40321968 -0.6508823
[14,] -0.80999580 -1.52283305  1.4729576
[15,]  0.20805934  0.25974308 -1.6093478
[16,]  0.03036708 -0.04013730  0.1686006

and I wrote the code
de[which(is.na(de))]<-sapply(seq_len(ncol(de)),function(i) {mean(de[,i],na.rm=TRUE)})

I get as the result
[,1]        [,2]       [,3]
[1,] -0.50575168 -0.26928087 -0.1192078
[2,] -0.12222376  1.20925752  0.9325334
[3,] -0.13412312  0.38012008 -1.8927164
[4,] -0.50575168 -0.41778861  1.4330507
[5,] -0.12222376 -0.49677462  0.2892706
[6,] -0.13412312 -0.13248754  1.3976522
[7,] -0.50575168 -0.54179054  0.2295291
[8,] -0.12222376  0.35788624 -0.5009389
[9,]  0.27500571 -0.41467591 -0.3426560
[10,] -3.07568579 -0.59234248 -0.8439027
[11,] -0.42240954  0.73642396 -0.4971999
[12,] -0.26901731 -0.06768044 -1.6127122
[13,]  0.01766284 -0.40321968 -0.6508823
[14,] -0.80999580 -1.52283305  1.4729576
[15,]  0.20805934  0.25974308 -1.6093478
[16,]  0.03036708 -0.04013730  0.1686006

It has replaced the NA values in first column with mean of first
column -0.505... and second cell with mean of second column etc.
I want to have the result like this:
[,1]        [,2]       [,3]
[1,] -0.50575168 -0.26928087 -0.1192078
[2,] -0.50575168  1.20925752  0.9325334
[3,] -0.50575168  0.38012008 -1.8927164
[4,] -0.50575168 -0.41778861  1.4330507
[5,] -0.50575168 -0.49677462  0.2892706
[6,] -0.50575168 -0.13248754  1.3976522
[7,] -0.50575168 -0.54179054  0.2295291
[8,] -0.50575168  0.35788624 -0.5009389
[9,]  0.27500571 -0.41467591 -0.3426560
[10,] -3.07568579 -0.59234248 -0.8439027
[11,] -0.42240954  0.73642396 -0.4971999
[12,] -0.26901731 -0.06768044 -1.6127122
[13,]  0.01766284 -0.40321968 -0.6508823
[14,] -0.80999580 -1.52283305  1.4729576
[15,]  0.20805934  0.25974308 -1.6093478
[16,]  0.03036708 -0.04013730  0.1686006