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Curtis Burkhalter

2012-Jun-11 19:44 UTC

[R] replacing values of matrix with random values of another dataframe

Hello,

I'm having trouble performing a certain function within R and I was hoping
someone might be able to help.  I have a matrix (1000x21) that contains
whole-number values ranging from 1-7 and I want to replace all entries
within this matrix that have a value of 1 with a random number contained
within a different dataframe that has 21 rows,1000 columns.  I've tried
using the if/else function, but this always seems to return a list with
strange output.  I've also tried using the "replace" and
"apply" functions,
but can't seem to get anything to work. My code is as follows:

#create data frame of 21000 random values

m_good_initial=rnorm(21000,2.79,0.18)
m_good_D1=ifelse(m_good_initial<0,0,m_good_initial)
m_good_D1mat=matrix(m_good_D1,byrow=T,21)
m_good_D1=as.data.frame(m_good_D1mat)

#create matrix of (1000x21) that contains whole-number values ranging from
1-7
#using sample to select values with a respective probability
search_strat_good <-
sample(landscenarios,1000,replace=T,prob=com_avgpgood[1,])
for (i in 2:21) {

        search_strat_good <-
cbind(search_strat_good,sample(landscenarios,1000,replace=T,prob=com_avgpgood[i,]))
}

#replace all search strategies of value "1" within matrix
"search_strat_good"
#with a random value from dataframe "m_good_D1"

bengood1=ifelse(search_strat_good==1,sample(m_good_D1,replace=F),search_strat_good)

Any help would be greatly appreciated.
-- 
Curtis Burkhalter

	[[alternative HTML version deleted]]

arun

2012-Jun-11 21:31 UTC

head link

[R] replacing values of matrix with random values of another dataframe

Hi,

Not sure if this is what you want.

?dat1<-matrix(sample(1:7,70,replace=TRUE),ncol=10,byrow=FALSE)
?dat2<-matrix(sample(1:7,70,replace=TRUE),ncol=7,byrow=FALSE)


?dat1[dat1[,1:10]==1]<-NA> dat1???? [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]??? 3??? 4??? 3??? 2??? 3??? 7??? 6??? 2??? 4???? 3
[2,]??? 2??? 5?? NA??? 7??? 2??? 4??? 2??? 5??? 4???? 6
[3,]??? 7?? NA??? 2??? 2??? 5??? 7??? 2??? 6??? 7???? 3
[4,]?? NA??? 5??? 2??? 5?? NA??? 6??? 5??? 5?? NA???? 7
[5,]??? 5??? 5??? 6??? 5??? 7??? 6??? 4??? 4??? 7???? 6
[6,]??? 5??? 7??? 5?? NA??? 6??? 5??? 3??? 6??? 3???? 2
[7,]??? 3??? 7?? NA??? 3??? 2??? 4??? 7??? 4??? 5???? 7




?dat1[is.na(dat1)]<-sample(dat2[,1:7])



?dat1
???? [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
[1,]??? 3??? 4??? 3??? 2??? 3??? 7??? 6??? 2??? 4???? 3
[2,]??? 2??? 5??? 1??? 7??? 2??? 4??? 2??? 5??? 4???? 6
[3,]??? 7??? 7??? 2??? 2??? 5??? 7??? 2??? 6??? 7???? 3
[4,]??? 1??? 5??? 2??? 5??? 1??? 6??? 5??? 5??? 1???? 7
[5,]??? 5??? 5??? 6??? 5??? 7??? 6??? 4??? 4??? 7???? 6
[6,]??? 5??? 7??? 5??? 3??? 6??? 5??? 3??? 6??? 3???? 2
[7,]??? 3??? 7??? 4??? 3??? 2??? 4??? 7??? 4??? 5???? 7

A.K.








----- Original Message -----
From: Curtis Burkhalter <curtisburkhalter at gmail.com>
To: r-help at r-project.org
Cc: 
Sent: Monday, June 11, 2012 3:44 PM
Subject: [R] replacing values of matrix with random values of another dataframe

Hello,

I'm having trouble performing a certain function within R and I was hoping
someone might be able to help.? I have a matrix (1000x21) that contains
whole-number values ranging from 1-7 and I want to replace all entries
within this matrix that have a value of 1 with a random number contained
within a different dataframe that has 21 rows,1000 columns.? I've tried
using the if/else function, but this always seems to return a list with
strange output.? I've also tried using the "replace" and
"apply" functions,
but can't seem to get anything to work. My code is as follows:

#create data frame of 21000 random values

m_good_initial=rnorm(21000,2.79,0.18)
m_good_D1=ifelse(m_good_initial<0,0,m_good_initial)
m_good_D1mat=matrix(m_good_D1,byrow=T,21)
m_good_D1=as.data.frame(m_good_D1mat)

#create matrix of (1000x21) that contains whole-number values ranging from
1-7
#using sample to select values with a respective probability
search_strat_good <-
sample(landscenarios,1000,replace=T,prob=com_avgpgood[1,])
for (i in 2:21) {

? ? ? ? search_strat_good <-
cbind(search_strat_good,sample(landscenarios,1000,replace=T,prob=com_avgpgood[i,]))
}

#replace all search strategies of value "1" within matrix
"search_strat_good"
#with a random value from dataframe "m_good_D1"

bengood1=ifelse(search_strat_good==1,sample(m_good_D1,replace=F),search_strat_good)

Any help would be greatly appreciated.
-- 
Curtis Burkhalter

??? [[alternative HTML version deleted]]

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.

Sarah Goslee

2012-Jun-11 21:32 UTC

head link

[R] replacing values of matrix with random values of another dataframe

Hi Curtis,

This isn't quite a reproducible example, though very close. As far as
I can tell, you're over-thinking it.

Instead of:
bengood1=ifelse(search_strat_good==1,sample(m_good_D1,replace=F),search_strat_good)

bengood1 <- search_strat_good
bengood1[bengood1 == 1] <- sample(m_good_D1, size=sum(bengood1 == 1),
replace=FALSE)

I made a couple other comments inline:

On Mon, Jun 11, 2012 at 3:44 PM, Curtis Burkhalter
<curtisburkhalter at gmail.com> wrote:> Hello,
>
> I'm having trouble performing a certain function within R and I was
hoping
> someone might be able to help. ?I have a matrix (1000x21) that contains
> whole-number values ranging from 1-7 and I want to replace all entries
> within this matrix that have a value of 1 with a random number contained
> within a different dataframe that has 21 rows,1000 columns. ?I've tried
> using the if/else function, but this always seems to return a list with
> strange output. ?I've also tried using the "replace" and
"apply" functions,
> but can't seem to get anything to work. My code is as follows:
>
> #create data frame of 21000 random values
>
> m_good_initial=rnorm(21000,2.79,0.18)
> m_good_D1=ifelse(m_good_initial<0,0,m_good_initial)
Again, you don't need the ifelse:
m_good_D1 <- m_good_initial
m_good_D1[m_good_D1 < 0] <- 0
> m_good_D1mat=matrix(m_good_D1,byrow=T,21)
> m_good_D1=as.data.frame(m_good_D1mat)
>
> #create matrix of (1000x21) that contains whole-number values ranging from
> 1-7
> #using sample to select values with a respective probability
> search_strat_good <-
> sample(landscenarios,1000,replace=T,prob=com_avgpgood[1,])
> for (i in 2:21) {
>
> ? ? ? ?search_strat_good <-
>
cbind(search_strat_good,sample(landscenarios,1000,replace=T,prob=com_avgpgood[i,]))
> }
Using cbind is a lot less efficient than creating a matrix of the
desired size beforehand and filling in each column.

Neater yet:
search_strat_good <- sapply(1:21,
function(i)sample(landscenarios,1000,replace=T,prob=com_avgpgood[i,]))
> #replace all search strategies of value "1" within matrix
> "search_strat_good"
> #with a random value from dataframe "m_good_D1"
>
>
bengood1=ifelse(search_strat_good==1,sample(m_good_D1,replace=F),search_strat_good)
>
> Any help would be greatly appreciated.
> --
> Curtis Burkhalter
>

-- 
Sarah Goslee
http://www.functionaldiversity.org

R help - Jun 2012 - replacing values of matrix with random values of another dataframe

[R] replacing values of matrix with random values of another dataframe

[R] replacing values of matrix with random values of another dataframe

[R] replacing values of matrix with random values of another dataframe

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