# [R] Using sapply instead of for loop

Charles Determan Jr deter088 at umn.edu
Wed Nov 19 17:34:42 CET 2014

```The following provides array A with 3.212016 as the last value.  The error
values are indeed in the array here.  There is also another with 6.281757
that I noticed at first glance.

errf<-function(act, res, testsize, flag)
{
j=1
if(flag==1)
{
j<-nrow(d)-testsize
}

print(act)
print(res)
print(flag)
diff<-0
s<-0
# loop for iterating to each value of the actual value and finding the
difference with thepredicted value
for (mn in 1:length(act))
{
cat("Value of mn in err", mn)
cat("Value of j in err", j)
cat("Value of res[j] in err", res[j])
diff<-(act[mn]-res[j])
print(act[mn])
print(res[j])
print(diff)
s<-s+(diff*diff)

j<-j+1
}

er1<-sqrt(s/length(act)) #forecasting error
print(er1)
return(er1)
}

far<-function(p, i, j, k, l, m, n, ervalue)
{
flagarima=0
testsize1 = 5
cat("does it come here value of p", p)
tryCatch({
air.model <-Arima(tsa,order=c(i-1,j-1,k-1),
seasonal=list(order=c(l-1,m-1,n-1),period=p-1), lambda=-0.254)  # the arima
model  # the arima model

f<- forecast(air.model,h=testsize1) # for getting the error

ervalue[i,j,k,l,m,n,p]<-errf(act1,f\$mean,testsize1,flagarima)

}, error=function(e)
{

return(NA)
}
)
cat("Value of error", ervalue[i,j,k,l,m,n,p])
cat("Value of i,j,k,l,m,n,p", i, j, k, l, m, n,p)
print(ervalue)
return(ervalue)
}
---------------------------

library('TTR')
library('forecast')
library('timeSeries')
library('xts')
library('RODBC')

maxval=2  # set the array size as well as the maximum parameter value here.
pmax=maxval  # set max p value of the ARIMA model
dmax=maxval  # set max d value of the ARIMA model
qmax=maxval  # set max q value of the ARIMA model
Pmax=maxval  # set max P value of the ARIMA model
Dmax=maxval  # set max D value of the ARIMA model
Qmax=maxval  # set max Q value of the ARIMA model
Permax=2     # maximum value of period.
freq=12
d<-c(3, 2, 5,29, 6, 10, 8, 4, 4, 5, 4, 6, 6, 1, 2, 3,5, 6, 9, 10)
st=2013   # start year value for getting the time series
month=4
tsa<-ts(d, frequency=freq, start=c(st,month))  # store the data in tsa as
the time
testsize1=5
act1<-d[16:20] # the array of actual values, the forecasted values will be
compared against these values

A<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) # depdending on
the max value set the , also it stores the AIC valuearray size
er<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval,2)) # depdending on
the max value set the , stores the error value.array size
ervalue<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
depdending on the max value set the , stores the error value.array size
erval1<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
depdending on the max value set the , stores the error value.array size
for (i in 1:pmax)
{
for (j in 1:dmax)
{
for (k in 1:qmax)
{
for (l in 1:Pmax)
{
for (m in 1:Dmax)
{
for (n in 1:Qmax)
{
A<-sapply((1:Permax),function(p) far(p, i, j, k, l, m,n,
ervalue),simplify=FALSE)

}
}
}
}
}  #for looping through period value
}

A

On Wed, Nov 19, 2014 at 9:46 AM, Amit Thombre <amitmt at techmahindra.com>
wrote:

>  Charles,
>
> Some variables were missing in the code. I have put them in this code. Now
> what happens is the value of cat("Value of error", ervalue[i,j,k,l,m,n,p])
> gives error value for various runs but they are not in the final Array A.
> You will have to go through the runs carefully. The array ervalue which is
> printed shows the value only for that run with previous values as NA. It is
> like with every new value of p the previous values of ervalue are lost.
> Just for confirmation the A and ervalue array has the last value as
> 3.212016. This si just for information so that you can confirm if you are
> getting this value.
>
> ----------------------------------------------------------------------------------------------
>
> errf<-function(act, res, testsize, flag)
> {
> j=1
> if(flag==1)
> {
> j<-nrow(d)-testsize
> }
>
> print(act)
> print(res)
> print(flag)
> diff<-0
> s<-0
> # loop for iterating to each value of the actual value and finding the
> difference with thepredicted value
> for (mn in 1:length(act))
> {
> cat("Value of mn in err", mn)
> cat("Value of j in err", j)
> cat("Value of res[j] in err", res[j])
> diff<-(act[mn]-res[j])
> print(act[mn])
> print(res[j])
> print(diff)
> s<-s+(diff*diff)
>
> j<-j+1
> }
>
> er1<-sqrt(s/length(act)) #forecasting error
> print(er1)
> return(er1)
> }
>
>
>
> far<-function(p)
> {
> flagarima=0
> cat("does it come here value of p", p)
> tryCatch({
> air.model <-Arima(tsa,order=c(i-1,j-1,k-1),
> seasonal=list(order=c(l-1,m-1,n-1),period=p-1), lambda=-0.254)  # the arima
> model
>
> f<- forecast(air.model,h=5) # for getting the error
>
> ervalue[i,j,k,l,m,n,p]<-errf(act1,f\$mean,testsize1,flagarima)
>
> }, error=function(e)
> {
>
> return(NA)
> }
> )
> cat("Value of error", ervalue[i,j,k,l,m,n,p])
> cat("Value of i,j,k,l,m,n,p", i, j, k, l, m, n,p)
> print(ervalue)
> return(ervalue)
> }
> ---------------------------
> library('TTR')
> library('forecast')
> library('timeSeries')
> library('xts')
> library('RODBC')
>
>
> maxval=2  # set the array size as well as the maximum parameter value here.
> pmax=maxval  # set max p value of the ARIMA model
> dmax=maxval  # set max d value of the ARIMA model
> qmax=maxval  # set max q value of the ARIMA model
> Pmax=maxval  # set max P value of the ARIMA model
> Dmax=maxval  # set max D value of the ARIMA model
> Qmax=maxval  # set max Q value of the ARIMA model
> Permax=2     # maximum value of period.
> freq=12
> d<-c(3, 2, 5,29, 6, 10, 8, 4, 4, 5, 4, 6, 6, 1, 2, 3,5, 6, 9, 10)
> st=2013   # start year value for getting the time series
> month=4
> tsa<-ts(d, frequency=freq, start=c(st,month))  # store the data in tsa as
> the time
> testsize1=5
> act1<-d[16:20] # the array of actual values, the forecasted values will be
> compared against these values
>
>
>
> A<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) # depdending
> on the max value set the , also it stores the AIC valuearray size
> er<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval,2)) # depdending
> on the max value set the , stores the error value.array size
> ervalue<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
> depdending on the max value set the , stores the error value.array size
> erval1<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
> depdending on the max value set the , stores the error value.array size
> for (i in 1:pmax)
> {
> for (j in 1:dmax)
> {
> for (k in 1:qmax)
> {
> for (l in 1:Pmax)
> {
> for (m in 1:Dmax)
> {
> for (n in 1:Qmax)
> {
> A<-sapply((1:Permax),function(p) far(p),simplify=FALSE)
>
> }
> }
> }
> }
> }  #for looping through period value
> }
>
>
>
>
>
>
>
>
>
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>
>
>
>
>
>
>
>
>
>
>
>  ------------------------------
> *From:* Charles Determan Jr [deter088 at umn.edu]
> *Sent:* Wednesday, November 19, 2014 8:40 PM
>
> *To:* Amit Thombre
> *Cc:* r-help at r-project.org
> *Subject:* Re: [R] Using sapply instead of for loop
>
>   Amit,
>
>  Even if you aren't getting an error with your original global variables
> it is far better practice to avoid global variables to make you code much
> more stable.  Of course you ultimately get to decide how your code is
> written.
>
>  That said, your error from the modified far function to include the
> variables is because you added too much to the sapply statement.  Here is
> what it should look like:
>
>              A<-sapply((1:Permax),function(p) far(p, i, j, k, l, m,n,
> ervalue),simplify=FALSE)
>
>  You can think apply statements as nothing more than a for loop that has
> been made 'pretty'.  You wanted to iterate from 1:Permax and use the other
> variables, therefore you only have the anonymous function (i.e.
> function(p)) only include the iterator and supply the other values from
> your nested for loops to the function.  When I run this with you code,
> making sure the function accepts the extra parameters, the A array appears
> to fill appropriately whereby most are 'NA' as specified by your 'far'
> function.  Is this what you expect?
>
>
> On Wed, Nov 19, 2014 at 8:16 AM, Amit Thombre <amitmt at techmahindra.com>
> wrote:
>
>>  Charles ,
>>
>> I am not getting an error . The final array A does not have the values in
>> it. Here is the reproducible code.  I have even tried using paasing ervalue
>> as a parameter to the function far.
>>
>>
>> -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>>
>> errf<-function(act, res, testsize, flag)
>> {
>> j=1
>> if(flag==1)
>> {
>> j<-nrow(d)-testsize
>> }
>>
>> print(act)
>> print(res)
>> print(flag)
>> diff<-0
>> s<-0
>> # loop for iterating to each value of the actual value and finding the
>> difference with thepredicted value
>> for (mn in 1:length(act))
>> {
>> cat("Value of mn in err", mn)
>> cat("Value of j in err", j)
>> cat("Value of res[j] in err", res[j])
>> diff<-(act[mn]-res[j])
>> print(act[mn])
>> print(res[j])
>> print(diff)
>> s<-s+(diff*diff)
>>
>> j<-j+1
>> }
>>
>> er1<-sqrt(s/length(act)) #forecasting error
>> print(er1)
>> return(er1)
>> }
>>
>>
>>
>> far<-function(p)
>> {
>>
>> cat("does it come here value of p", p)
>> tryCatch({
>> air.model <-Arima(tsa,order=c(i-1,j-1,k-1),
>> seasonal=list(order=c(l-1,m-1,n-1),period=p-1), lambda=lbda)  # the arima
>> model
>>
>> f<- forecast(air.model,h=testsize1) # for getting the error
>>
>> ervalue[i,j,k,l,m,n,p]<-errf(act1,f\$mean,testsize1,flagarima)
>>
>> }, error=function(e)
>> {
>>
>> return(NA)
>> }
>> )
>> cat("Value of error", ervalue[i,j,k,l,m,n,p])
>> cat("Value of i,j,k,l,m,n,p", i, j, k, l, m, n,p)
>> print(ervalue)
>> return(ervalue)
>> }
>>  ---------------------------
>> library('TTR')
>> library('forecast')
>> library('timeSeries')
>> library('xts')
>> library('RODBC')
>>
>>
>>  maxval=2  # set the array size as well as the maximum parameter value
>> here.
>> pmax=maxval  # set max p value of the ARIMA model
>> dmax=maxval  # set max d value of the ARIMA model
>> qmax=maxval  # set max q value of the ARIMA model
>> Pmax=maxval  # set max P value of the ARIMA model
>> Dmax=maxval  # set max D value of the ARIMA model
>> Qmax=maxval  # set max Q value of the ARIMA model
>> Permax=2     # maximum value of period.
>>  freq=12
>> d<-c(10, 13, 14, 4, 5, 6, 7, 10, 12, 13, 14, 20, 3, 4, 5, 19, 23, 21, 18,
>> 19, 21, 14, 15, 16, 17, 12, 20, 19, 17)
>> st=2013   # start year value for getting the time series
>> month=4
>> tsa<-ts(d, frequency=freq, start=c(st,month))  # store the data in tsa
>> as  the time
>>
>> A<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) # depdending
>> on the max value set the , also it stores the AIC valuearray size
>> er<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval,2)) # depdending
>> on the max value set the , stores the error value.array size
>> ervalue<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
>> depdending on the max value set the , stores the error value.array size
>> erval1<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
>> depdending on the max value set the , stores the error value.array size
>> for (i in 1:pmax)
>> {
>> for (j in 1:dmax)
>> {
>> for (k in 1:qmax)
>> {
>> for (l in 1:Pmax)
>> {
>> for (m in 1:Dmax)
>> {
>> for (n in 1:Qmax)
>> {
>>  A<-sapply((1:Permax),function(p) far(p),simplify=FALSE)
>>
>> }
>> }
>> }
>> }
>> }  #for looping through period value
>> }
>>
>>
>>
>>
>>
>>  ------------------------------
>> *From:* Charles Determan Jr [deter088 at umn.edu]
>> *Sent:* Wednesday, November 19, 2014 7:05 PM
>> *To:* Amit Thombre
>> *Cc:* r-help at r-project.org
>> *Subject:* Re: [R] Using sapply instead of for loop
>>
>>    Amit,
>>
>>  Your question isn't necessarily complete.  You haven't provided a
>> reproducible example of your data or an error message.  At first glance you
>> aren't passing anything to your 'far' function except for 'p' and yet it
>> uses i,j,k,l,m,n,testsize1, and act1.  You should generally try to avoid
>> global variables as they can lead to broken code.  You should redefine your
>> function with all the needed parameters and try again.
>>
>>  Regards,
>>
>> On Wed, Nov 19, 2014 at 3:47 AM, Amit Thombre <amitmt at techmahindra.com>
>> wrote:
>>
>>> I am trying to replace a for loop by using sapply, The code is for
>>> forecasting using arima. The code is as follows:-
>>> -------------------------------------------------------
>>> far<-function(p)
>>> {
>>>
>>> cat("does it come here value of p", p)
>>> tryCatch({
>>> air.model <-Arima(tsa,order=c(i-1,j-1,k-1),
>>> seasonal=list(order=c(l-1,m-1,n-1),period=p-1), lambda=lbda)  # the arima
>>> model
>>>
>>> f<- forecast(air.model,h=testsize1) # for getting the error
>>>
>>> ervalue[i,j,k,l,m,n,p]<-errf(act1,f\$mean,testsize1,flagarima)
>>>
>>> }, error=function(e)
>>> {
>>>
>>> return(NA)
>>> }
>>> )
>>> cat("Value of error", ervalue[i,j,k,l,m,n,p])
>>> cat("Value of i,j,k,l,m,n,p", i, j, k, l, m, n,p)
>>> print(ervalue)
>>> return(ervalue)
>>> }
>>> ---------------------------
>>> maxval=2  # set the array size as well as the maximum parameter value
>>> here.
>>> pmax=maxval  # set max p value of the ARIMA model
>>> dmax=maxval  # set max d value of the ARIMA model
>>> qmax=maxval  # set max q value of the ARIMA model
>>> Pmax=maxval  # set max P value of the ARIMA model
>>> Dmax=maxval  # set max D value of the ARIMA model
>>> Qmax=maxval  # set max Q value of the ARIMA model
>>> Permax=2     # maximum value of period.
>>>
>>> st=2013   # start year value for getting the time series
>>> month=4 d<-c(10, 13, 14, 4, 5, 6, 7, 10, 12, 13, 14, 20, 3, 4, 5, 19,
>>> 23, 21, 18, 19, 21, 14, 15, 16, 17, 12, 20, 19, 17)
>>> tsa<-ts(d, frequency=freq, start=c(st,month))  # store the data in tsa
>>> as  the time
>>>
>>> A<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) # depdending
>>> on the max value set the , also it stores the AIC valuearray size
>>> ervalue<-array(, c(maxval,maxval,maxval,maxval,maxval,maxval, 2)) #
>>> depdending on the max value set the , stores the error value.array size
>>>
>>> for (i in 1:pmax)
>>> {
>>> for (j in 1:dmax)
>>> {
>>> for (k in 1:qmax)
>>> {
>>> for (l in 1:Pmax)
>>> {
>>> for (m in 1:Dmax)
>>> {
>>> for (n in 1:Qmax)
>>> {
>>> A<-sapply((1:Permax),function(p) far(p),simplify=FALSE)
>>>
>>> }
>>> }
>>> }
>>> }
>>> }  #for looping through period value
>>> }
>>> ------------------------------------------------------------------
>>> The sapply replaces the for loop
>>> for (p in 1:Permax)
>>> {
>>> cat("does it come here value of p", p)
>>> tryCatch({
>>> air.model <-Arima(tsa,order=c(i-1,j-1,k-1),
>>> seasonal=list(order=c(l-1,m-1,n-1),period=p), lambda=lbda)  # the arima
>>> model
>>> A[i,j,k,l,m,n,p]<-AIC(air.model)
>>> f<- forecast(air.model,h=testsize1) # for getting the error
>>> er[i,j,k,l,m,n,p]<-errf(act1,f\$mean,testsize1,flagarima)
>>> }, error=function(e)
>>> {
>>>
>>> return(NA)
>>> }
>>> )
>>>  cat("Value of error", er[i,j,k,l,m,n,p])
>>>  cat("Value of i,j,k,l,m,n,p", i, j, k, l, m, n,p)
>>> }
>>>
>>> --------------------------------------------------------------------------
>>> Now the er[I,j,k,l,m,n,p] I.e the error get populated but on every call
>>> to the function far() the array loses the previous value and gets replaced
>>> with NA and gets the newly calculated error value. Finally the array A gets
>>> populated with only the latest value and does not hold the old values.
>>>
>>>
>>>
>>> ============================================================================================================================
>>> Disclaimer:  This message and the information contained herein is
>>> proprietary and confidential and subject to the Tech Mahindra policy
>>> statement, you may review the policy at
>>> http://www.techmahindra.com/Disclaimer.html externally
>>> http://tim.techmahindra.com/tim/disclaimer.html internally within
>>> TechMahindra.
>>>
>>> ============================================================================================================================
>>>
>>>
>>>         [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
>>> R-help at r-project.org mailing list
>>> https://stat.ethz.ch/mailman/listinfo/r-help
>>> http://www.R-project.org/posting-guide.html
>>> and provide commented, minimal, self-contained, reproducible code.
>>>
>>
>>
>>
>>  --
>>  Dr. Charles Determan, PhD
>> Integrated Biosciences
>>
>> ------------------------------
>>
>> ============================================================================================================================
>> Disclaimer: This message and the information contained herein is
>> proprietary and confidential and subject to the Tech Mahindra policy
>> statement, you may review the policy at
>> http://www.techmahindra.com/Disclaimer.html externally
>> http://tim.techmahindra.com/tim/disclaimer.html internally within
>> TechMahindra.
>>
>> ============================================================================================================================
>>
>>
>
>
>  --
>  Dr. Charles Determan, PhD
> Integrated Biosciences
>
> ------------------------------
>
> ============================================================================================================================
> Disclaimer: This message and the information contained herein is
> proprietary and confidential and subject to the Tech Mahindra policy
> statement, you may review the policy at
> http://www.techmahindra.com/Disclaimer.html externally
> http://tim.techmahindra.com/tim/disclaimer.html internally within
> TechMahindra.
>
> ============================================================================================================================
>
>

--
Dr. Charles Determan, PhD
Integrated Biosciences

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```