# [R] threshold matrix

David Winsemius dwinsemius at comcast.net
Fri Apr 29 19:16:37 CEST 2011

```On Apr 29, 2011, at 10:44 AM, Alaios wrote:

> Thanks a lot.
> I finally used
>
> M2 <- M
> M2[M < thresh] <- 0
> M2[M >= thresh] <- 1
>
> as I noticed that this one line
>
> M2 <- as.numeric( M[] < thresh )
> vectorizes my matrix.
>
> One more question I have two matrices that only differ slightly.
> What will be the easiest way to compare and find the cells that are
> not the same?

M[!M==N]
N[!M==N]

>
> Best Regards
> Alex
>
> --- On Fri, 4/29/11, David Winsemius <dwinsemius at comcast.net> wrote:
>
>> From: David Winsemius <dwinsemius at comcast.net>
>> Subject: Re: [R] threshold matrix
>> To: "Alaios" <alaios at yahoo.com>
>> Cc: R-help at r-project.org
>> Date: Friday, April 29, 2011, 2:57 PM
>>
>> On Apr 29, 2011, at 9:37 AM, Alaios wrote:
>>
>>> Dear all,
>>> I have a quite big matrix which I would like to
>> threshold.
>>> If the value is below threshold the cell should be
>> zero
>>> and
>>> if the value is over threshold the cell should be one
>>
>> M2 <- M
>> M2[M < thresh] <- 0
>> M2[M >= thresh] <- 1
>>
>> or perhaps simply:
>>
>> M2 <- as.numeric( M[] < thresh )
>>>
>>> One really simple way to do that is two have a nested
>> loop and check cell by cell.
>>>
>>> The problem is that this seems to be really time
>> consuming and ineficient.
>>>
>>> What do you suggest me to try out?
>>
>> --
>> David Winsemius, MD
>> West Hartford, CT
>>
>>

David Winsemius, MD
West Hartford, CT

```