Hi all,
I'm trying to write 2 functions(as a part of a larger code) to evaluate a
certain equation. The function is :
X= c (0.3893094 2.0962311 2.6007558 3.0761810 3.3246947 3.3917976
4.1981546 6.8826140 12.3128013 15.5588470)
R=c (0 1 0 0 0 1 1 1 0 1)
alpha.update=function(X, R, alpha.curr, beta.curr=1 ,m=10,
hyp=c(3,15,6,22.5))
{
o<-numeric(m)
for (i in 1:m) {
o[i]<- (1+R[i])*((X[i])^(beta.curr))
}
sh<-sum(o) + hyp[2] + (hyp[4]* beta.curr)
rg<-rgamma(1, shape= m+hyp[1]+hyp[3] , rate = sh )
return(rg)
}
alpha.curr<- alpha.update(X, R, alpha.curr=0.2, beta.curr=1 ,m, hyp)
bettarg<- function(X, R, alpha.curr, beta.curr=1 ,m=10,
hyp=c(3,15,6,22.5))
{
o<-numeric(m)
for (i in 1:m) {
o[i]<- (1+R[i])*((X[i])^( beta.curr))
}
logbt<- log(beta.curr ^(m+hyp[3]-1)) + log(prod((X)^( beta.curr -1)))
+ (-1*alpha.curr *(sum(o) + (hyp[4]* beta.curr)))
bt<- exp(logbt)
return(bt)
}
The problem is that the function bettarg() sometimes produces NaN, and
this stops the evaluation of my equation, so how can I force it to ignore
the NaNs produced and repeat the evaluation again till it prroduces a
number?
Thanks in advance,
Maram Salem
[[alternative HTML version deleted]]
You can do things like
while ( !is.nan( r <- randomFunction(x) )) {}
# r will be a non-NaN value of randomFunction(x) now
or
for(i in seq_len(1000)) {
if (!is.nan( r <- randomFunction(x))) {
break
}
if (i == 1000) {
stop("no good values of randomFunction(x) in 1000 tries")
}
}
to avoid infinite loops when randomFunction [almost] always produces a NaN.
You may be able to avoid some NaNs by replacing log(b^n) with n*log(b) and
log(prod(x^b)) with sum(b*log(x)). That would avoid unneeded Inf values,
which
can lead to NaN down the line (Inf-Inf -> NaN, Inf/Inf -> NaN).
Bill Dunlap
TIBCO Software
wdunlap tibco.com
On Sun, Feb 14, 2016 at 9:22 AM, Maram SAlem <marammagdysalem at
gmail.com>
wrote:
> Hi all,
>
> I'm trying to write 2 functions(as a part of a larger code) to evaluate
a
> certain equation. The function is :
>
> X= c (0.3893094 2.0962311 2.6007558 3.0761810 3.3246947 3.3917976
> 4.1981546 6.8826140 12.3128013 15.5588470)
> R=c (0 1 0 0 0 1 1 1 0 1)
>
> alpha.update=function(X, R, alpha.curr, beta.curr=1 ,m=10,
> hyp=c(3,15,6,22.5))
>
> {
>
> o<-numeric(m)
>
> for (i in 1:m) {
>
> o[i]<- (1+R[i])*((X[i])^(beta.curr))
>
> }
>
> sh<-sum(o) + hyp[2] + (hyp[4]* beta.curr)
>
> rg<-rgamma(1, shape= m+hyp[1]+hyp[3] , rate = sh )
>
> return(rg)
>
> }
>
>
> alpha.curr<- alpha.update(X, R, alpha.curr=0.2, beta.curr=1 ,m, hyp)
>
>
> bettarg<- function(X, R, alpha.curr, beta.curr=1 ,m=10,
> hyp=c(3,15,6,22.5))
>
> {
>
> o<-numeric(m)
>
> for (i in 1:m) {
>
> o[i]<- (1+R[i])*((X[i])^( beta.curr))
>
> }
>
> logbt<- log(beta.curr ^(m+hyp[3]-1)) + log(prod((X)^( beta.curr
-1)))
> + (-1*alpha.curr *(sum(o) + (hyp[4]* beta.curr)))
>
>
>
> bt<- exp(logbt)
>
> return(bt)
>
> }
>
>
> The problem is that the function bettarg() sometimes produces NaN, and
> this stops the evaluation of my equation, so how can I force it to ignore
> the NaNs produced and repeat the evaluation again till it prroduces a
> number?
>
>
> Thanks in advance,
>
>
> Maram Salem
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>
[[alternative HTML version deleted]]
Thanks for helping Dunlap.
I just don't get why does the function bettarg() executes well if I
evaluate it (by hand) step-by step . nut for the same input values , if I
tried to execute bettarg() it will give me the error
Error in if (y <= accept.prob) { : missing value where TRUE/FALSE needed
Although both y and accept.prob have values and are not missing.
Any help would be appreciated as this error is causing my entire(large and
complicated) code to stop execution.
Maram Salem
On 14 February 2016 at 22:08, William Dunlap <wdunlap at tibco.com> wrote:
> You can do things like
> while ( !is.nan( r <- randomFunction(x) )) {}
> # r will be a non-NaN value of randomFunction(x) now
> or
> for(i in seq_len(1000)) {
> if (!is.nan( r <- randomFunction(x))) {
> break
> }
> if (i == 1000) {
> stop("no good values of randomFunction(x) in 1000
tries")
> }
> }
> to avoid infinite loops when randomFunction [almost] always produces a NaN.
>
> You may be able to avoid some NaNs by replacing log(b^n) with n*log(b) and
> log(prod(x^b)) with sum(b*log(x)). That would avoid unneeded Inf values,
> which
> can lead to NaN down the line (Inf-Inf -> NaN, Inf/Inf -> NaN).
>
>
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
>
> On Sun, Feb 14, 2016 at 9:22 AM, Maram SAlem <marammagdysalem at
gmail.com>
> wrote:
>
>> Hi all,
>>
>> I'm trying to write 2 functions(as a part of a larger code) to
evaluate a
>> certain equation. The function is :
>>
>> X= c (0.3893094 2.0962311 2.6007558 3.0761810 3.3246947 3.3917976
>> 4.1981546 6.8826140 12.3128013 15.5588470)
>> R=c (0 1 0 0 0 1 1 1 0 1)
>>
>> alpha.update=function(X, R, alpha.curr, beta.curr=1 ,m=10,
>> hyp=c(3,15,6,22.5))
>>
>> {
>>
>> o<-numeric(m)
>>
>> for (i in 1:m) {
>>
>> o[i]<- (1+R[i])*((X[i])^(beta.curr))
>>
>> }
>>
>> sh<-sum(o) + hyp[2] + (hyp[4]* beta.curr)
>>
>> rg<-rgamma(1, shape= m+hyp[1]+hyp[3] , rate = sh )
>>
>> return(rg)
>>
>> }
>>
>>
>> alpha.curr<- alpha.update(X, R, alpha.curr=0.2, beta.curr=1 ,m, hyp)
>>
>>
>> bettarg<- function(X, R, alpha.curr, beta.curr=1 ,m=10,
>> hyp=c(3,15,6,22.5))
>>
>> {
>>
>> o<-numeric(m)
>>
>> for (i in 1:m) {
>>
>> o[i]<- (1+R[i])*((X[i])^( beta.curr))
>>
>> }
>>
>> logbt<- log(beta.curr ^(m+hyp[3]-1)) + log(prod((X)^(
beta.curr
>> -1)))
>> + (-1*alpha.curr *(sum(o) + (hyp[4]* beta.curr)))
>>
>>
>>
>> bt<- exp(logbt)
>>
>> return(bt)
>>
>> }
>>
>>
>> The problem is that the function bettarg() sometimes produces NaN,
and
>> this stops the evaluation of my equation, so how can I force it to
ignore
>> the NaNs produced and repeat the evaluation again till it prroduces a
>> number?
>>
>>
>> Thanks in advance,
>>
>>
>> Maram Salem
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> 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.
>>
>
>
[[alternative HTML version deleted]]