On 29-07-2013, at 18:39, "iza.ch1" <iza....@op.pl> wrote:
> 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
>
or this:
apply(de,2, function(x) {x[which(is.na(x))] <- mean(x,na.rm=TRUE);x})
Berend
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