# [R] CONFUSSING WITH select[!miss] <- 1:sum(!miss)

Jim Lemon drjimlemon at gmail.com
Tue Dec 6 22:06:16 CET 2016

```Hi Greg,
What is happening is easy to see:

ph<-matrix(sample(1:100,40),ncol=4)
colnames(ph)<-c("M1","X1","X2","X3")
ph[sample(1:10,3),1]<-NA
ph
M1 X1 X2 X3
[1,]  34 98  3 35
[2,]  13 66 74 68
[3,]  NA 22 99 79
[4,]  94  6 80 36
[5,]  18  9 16 65
[6,]  NA 29 56 90
[7,]  41 23  7 55
[8,] 100 93 71 70
[9,]  NA 61  8 57
[10,]  25  4 47 60
# get a logical vector showing which rows contain NA
miss <- apply(is.na(ph[,c("M1","X1","X2","X3")]),1, any)
miss
[1] FALSE FALSE  TRUE FALSE FALSE  TRUE FALSE FALSE  TRUE FALSE
# create a vector of zeros the length of the number of rows
select <- integer(nrow(ph))
select
[1] 0 0 0 0 0 0 0 0 0 0
# get the indices for the rows that do _not_ have NAs
select[!miss] <- 1:sum(!miss)
select
[1] 1 2 0 3 4 0 5 6 0 7

If this is to select the rows without NAs, it may be easier to do:

which(!miss)
[1]  1  2  4  5  7  8 10

Jim

On Wed, Dec 7, 2016 at 5:18 AM, greg holly <mak.hholly at gmail.com> wrote:
> Dear All;
>
> I am very new in R and try to understand the logic for a program has been
> run sucessfully. Here select[!miss] <- 1:sum(!miss) par is confussing me. I
> need to understandand the logic behind this commend line.
>
>
> Greg
>
>
> miss <- apply(is.na(ph[,c("M1","X1","X2","X3")]),1, any)
> select <- integer(nrow(ph))
> select[!miss] <- 1:sum(!miss)
>
>         [[alternative HTML version deleted]]
>
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