R help - Apr 2011 - count number of TRUEs in each row

Hi all, 

I have a huge matrix of TRUE/FALSE table like following, and I want to count
the number of TRUEs in each row. Instead of looping through each row and do
length(Z[Z==TRUE]), I am wondering if there is an easier way of doing this. 

       [,1]   [,2]    [,3]
[1,]TRUE FALSE FALSE
[2,]FALSE TRUE TRUE

Thank you in advance.
Wendy

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Ms Qiao,

On 10 April 2011 14:24, Wendy <wendy2.qiao@gmail.com> wrote:
> I have a huge matrix of TRUE/FALSE table like following, and I want to
> count
> the number of TRUEs in each row. Instead of looping through each row and do
> length(Z[Z==TRUE]), I am wondering if there is an easier way of doing this.
>
>       [,1]   [,2]    [,3]
> [1,]TRUE FALSE FALSE
> [2,]FALSE TRUE TRUE
>
Does this help...
Z[Z==T]
?

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On Sun, Apr 10, 2011 at 2:24 PM, Wendy <wendy2.qiao at gmail.com>
wrote:
> Hi all,
>
> I have a huge matrix of TRUE/FALSE table like following, and I want to
count
> the number of TRUEs in each row. Instead of looping through each row and do
> length(Z[Z==TRUE]), I am wondering if there is an easier way of doing this.
>
> ? ? ? [,1] ? [,2] ? ?[,3]
> [1,]TRUE FALSE FALSE
> [2,]FALSE TRUE TRUE
>
rowSums(Z)

Peter

Hi Wendy,

try this:
Z <- matrix(runif(1000)>0.5,10,100)
rowSums(Z)

HTH,
  Denes

> Hi all,
>
> I have a huge matrix of TRUE/FALSE table like following, and I want to
> count
> the number of TRUEs in each row. Instead of looping through each row and
> do
> length(Z[Z==TRUE]), I am wondering if there is an easier way of doing
> this.
>
>        [,1]   [,2]    [,3]
> [1,]TRUE FALSE FALSE
> [2,]FALSE TRUE TRUE
>
> Thank you in advance.
> Wendy
>
> --
> View this message in context:
>
http://r.789695.n4.nabble.com/count-number-of-TRUEs-in-each-row-tp3440486p3440486.html
> Sent from the R help mailing list archive at Nabble.com.
>
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