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

greg holly mak.hholly at gmail.com
Wed Dec 7 15:22:21 CET 2016

```Hi Jim, Rui and William;

I do appreciate for your explanations and help. These are very helpful.
Regards,

Hayrettin

On Tue, Dec 6, 2016 at 4:06 PM, Jim Lemon <drjimlemon at gmail.com> wrote:

> 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.
> >
> > Thanks in advance for your help,
> >
> > 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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>

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