if clause in data frame - R-help

arun

Fri, Mar 29, 2013 10:47 AM #

Hi,


final<-data.frame()
?? for (m1 in 4:10) {
?????? for (n1 in 4:10){? 
?????????? for (x1 in 0: m1) {
????????????? for (y1 in 0: n1) {

final<- rbind(final,c(m1,n1,x1,y1))
res}}}}
?final1<-within(final,{flag<-ifelse(x1/m1>y1/n1, 1,0)})
?head(final1)
#? m1 n1 x1 y1 flag
#1? 4? 4? 0? 0??? 0
#2? 4? 4? 0? 1??? 0
#3? 4? 4? 0? 2??? 0
#4? 4? 4? 0? 3??? 0
#5? 4? 4? 0? 4??? 0
#6? 4? 4? 1? 0??? 1


Also, just by looking at your code, you have "flag" and "flap".

A.K.

arun

Fri, Mar 29, 2013 10:48 AM #

Forgot:

colnames(final)<- c("m1","n1","x1","y1")

before;
final1<-within(final,{flag<-ifelse(x1/m1>y1/n1, 1,0)})


----- Original Message -----
From: arun <smartpink111 at yahoo.com>
To: Joanna Zhang <zjoanna2013 at gmail.com>
Cc: R help <r-help at r-project.org>
Sent: Friday, March 29, 2013 1:47 PM
Subject: Re: if clause in data frame

Hi,


final<-data.frame()
?? for (m1 in 4:10) {
?????? for (n1 in 4:10){? 
?????????? for (x1 in 0: m1) {
????????????? for (y1 in 0: n1) {

final<- rbind(final,c(m1,n1,x1,y1))
res}}}}
?final1<-within(final,{flag<-ifelse(x1/m1>y1/n1, 1,0)})
?head(final1)
#? m1 n1 x1 y1 flag
#1? 4? 4? 0? 0??? 0
#2? 4? 4? 0? 1??? 0
#3? 4? 4? 0? 2??? 0
#4? 4? 4? 0? 3??? 0
#5? 4? 4? 0? 4??? 0
#6? 4? 4? 1? 0??? 1


Also, just by looking at your code, you have "flag" and "flap".

A.K.

David Winsemius

Fri, Mar 29, 2013 1:46 PM #

On Mar 29, 2013, at 10:47 AM, arun wrote:

That looks likely to be extremely slow. 'rbind.data.frame' is notoriously slow when applied iteratively in loops.

Couldn't this just be:

dat <- expand.grid(m1 = 4:10, n1 = 4:10, x1 = 0: m1, y1 = 0: n1) 
final= within(dat, flag=as.numeric( x1/m1>y1/n1) )

David.

>  head(final1)
> #  m1 n1 x1 y1 flag
> #1  4  4  0  0    0
> #2  4  4  0  1    0
> #3  4  4  0  2    0
> #4  4  4  0  3    0
> #5  4  4  0  4    0
> #6  4  4  1  0    1
> 
> 
> Also, just by looking at your code, you have "flag" and "flap".
> 
> A.K.
> 
> 
> 
> ________________________________
> From: Joanna Zhang <zjoanna2013 at gmail.com>
> To: arun <smartpink111 at yahoo.com> 
> Sent: Friday, March 29, 2013 10:56 AM
> Subject: if clause in data frame
> 
> 
> Why the if clause code not working here?
> 
> final<-data.frame()
>    for (m1 in 4:10) {
>        for (n1 in 4:10){  
>            for (x1 in 0: m1) {
>               for (y1 in 0: n1) {
> 
> if (x1/m1>y1/n1)  { flag<-1}
> else {flap<-0}
> 
> final<-rbind(final, c(m1,n1,flag, x1,y1))
> }}
> }}
> colnames(final)<-c("m1","n1","flag","x1","y1") 
> final
> 


David Winsemius
Alameda, CA, USA

arun

Fri, Mar 29, 2013 1:48 PM #

Yes, that is better.

I just copied the same function that the OP used.
A.K.

David.

>? head(final1)
> #? m1 n1 x1 y1 flag
> #1? 4? 4? 0? 0? ? 0
> #2? 4? 4? 0? 1? ? 0
> #3? 4? 4? 0? 2? ? 0
> #4? 4? 4? 0? 3? ? 0
> #5? 4? 4? 0? 4? ? 0
> #6? 4? 4? 1? 0? ? 1
> 
> 
> Also, just by looking at your code, you have "flag" and "flap".
> 
> A.K.
> 
> 
> 
> ________________________________
> From: Joanna Zhang <zjoanna2013 at gmail.com>
> To: arun <smartpink111 at yahoo.com> 
> Sent: Friday, March 29, 2013 10:56 AM
> Subject: if clause in data frame
> 
> 
> Why the if clause code not working here?
> 
> final<-data.frame()
>? ? for (m1 in 4:10) {
>? ? ? ? for (n1 in 4:10){? 
>? ? ? ? ? ? for (x1 in 0: m1) {
>? ? ? ? ? ? ?  for (y1 in 0: n1) {
> 
> if (x1/m1>y1/n1)? { flag<-1}
> else {flap<-0}
> 
> final<-rbind(final, c(m1,n1,flag, x1,y1))
> }}
> }}
> colnames(final)<-c("m1","n1","flag","x1","y1") 
> final
> 


David Winsemius
Alameda, CA, USA

David Winsemius

Fri, Mar 29, 2013 1:51 PM #

On Mar 29, 2013, at 1:48 PM, arun wrote:

________________________________
From: David Winsemius <dwinsemius at comcast.net>
To: arun <smartpink111 at yahoo.com> 
Cc: Joanna Zhang <zjoanna2013 at gmail.com>; R help <r-help at r-project.org> 
Sent: Friday, March 29, 2013 4:46 PM
Subject: Re: [R] if clause in data frame


On Mar 29, 2013, at 10:47 AM, arun wrote:

Hi,


final<-data.frame()
    for (m1 in 4:10) {
        for (n1 in 4:10){  
            for (x1 in 0: m1) {
               for (y1 in 0: n1) {

final<- rbind(final,c(m1,n1,x1,y1))
res}}}}
  final1<-within(final,{flag<-ifelse(x1/m1>y1/n1, 1,0)})

That looks likely to be extremely slow. 'rbind.data.frame' is notoriously slow when applied iteratively in loops.

Couldn't this just be:

dat <- expand.grid(m1 = 4:10, n1 = 4:10, x1 = 0: m1, y1 = 0: n1) 
final= within(dat, flag=as.numeric( x1/m1>y1/n1) )

This may be one of those instances where "=" is not an acceptable replacement for "<-". I get an error with that code whereas I get the desired result with:

________________________________
From: Joanna Zhang <zjoanna2013 at gmail.com>
To: arun <smartpink111 at yahoo.com> 
Sent: Friday, March 29, 2013 10:56 AM
Subject: if clause in data frame


Why the if clause code not working here?

final<-data.frame()
    for (m1 in 4:10) {
        for (n1 in 4:10){  
            for (x1 in 0: m1) {
               for (y1 in 0: n1) {

if (x1/m1>y1/n1)  { flag<-1}
else {flap<-0}

final<-rbind(final, c(m1,n1,flag, x1,y1))
}}
}}
colnames(final)<-c("m1","n1","flag","x1","y1") 
final

David Winsemius
Alameda, CA, USA