[R] Arrange data

[Jim Lemon]

Hi Md,
I think the errors are that you forgot to initialize "m", calculated
the mean outside the loops and forgot the final brace:

m<-rep(0,44)
for(i in 1975:2017) {
  for(j in 1:44) {
   mddat2[j]<-mddat[mddat$Year == i & mddat$Month >= 7 |
      mddat$Year == (i+1) & mddat$Month <= 6,]
   m[j]=mean(mddat2$Value)
 }
}

Jim

On Wed, Aug 5, 2020 at 6:04 AM Md. Moyazzem Hossain <hossainmm using juniv.edu> wrote:
>
> Dear Jim,
>
> Thank you very much. You are right. It is good now. However, I want to continue it up to the year 2017.
>
> I use the following code but got the error
>
> for(i in 1975:2017){
>   for(j in 1:44){
> mddat2[j]<-mddat[mddat$Year == i & mddat$Month >= 7 |
>                 mddat$Year == (i+1) & mddat$Month <= 6,]
> }
> m[j]=mean(mddat2$Value)
>
> }
> m
>
> Please help me in this regard. Many thanks in advance.
>
> Regards,
> Md
>
> On Tue, Aug 4, 2020 at 8:41 AM Jim Lemon <drjimlemon using gmail.com> wrote:
>>
>> Your problem is in the subset operation. You have asked for a value of
>> month greater or equal to 7 and less than or equal to 6. You probably
>> got an error message that told you that the data were of length zero
>> or something similar. If you check the result of that statement:
>>
>> > mddat$month >= 7 & mddat$month <= 6
>> logical(0)
>>
>> In other words, the two logical statements when ANDed cannot produce a
>> result. A number cannot be greater than or equal to 7 AND less than or
>> equal to 6. What you want is:
>>
>> mddat2<-mddat[mddat$Year == 1975 & mddat$Month >= 7 |
>>  mddat$Year == 1976 & mddat$Month <= 6,]
>> mean(mddat2$Value)
>> [1] 88.91667
>>
>> Apart from that, your email client is inserting EOL characters that
>> cause an error when pasted into R.
>>
>> Error: unexpected input in "�"
>>
>> Probably due to MS Outlook, this has been happening quite a bit lately.
>>
>> Jim
>>
>> On Mon, Aug 3, 2020 at 11:30 PM Md. Moyazzem Hossain
>> <hossainmm using juniv.edu> wrote:
>> >
>> > Dear Jim,
>> >
>> > Thank you very much. It is working now.
>> >
>> > However, I am also trying to find the average of the value from July 1975 to June 1976 and recorded as the value for the year 1975 but got an error message. I am attaching the data file here. Please check the attachment.
>> >
>> > mddat=read.csv("F:/mddat.csv", header=TRUE)
>> > mddat2<-mddat[mddat$Month >=7 & mddat$Month <= 6,]
>> > jan2jun<-by(mddat2$Value,mddat2$Year,mean)
>> > jan2jun
>> >
>> > Please help me again and many thanks in advance.
>> >
>> > Md
>> >
>> >
>> > On Mon, Aug 3, 2020 at 12:33 PM Rasmus Liland <jral using posteo.no> wrote:
>> >>
>> >> On 2020-08-03 21:11 +1000, Jim Lemon wrote:
>> >> > On Mon, Aug 3, 2020 at 8:52 PM Md. Moyazzem Hossain <hossainmm using juniv.edu> wrote:
>> >> > >
>> >> > > Hi,
>> >> > >
>> >> > > I have a dataset having monthly
>> >> > > observations (from January to
>> >> > > December) over a period of time like
>> >> > > (2000 to 2018). Now, I am trying to
>> >> > > take an average the value from
>> >> > > January to July of each year.
>> >> > >
>> >> > > The data looks like
>> >> > > Year    Month  Value
>> >> > > 2000    1         25
>> >> > > 2000    2         28
>> >> > > 2000    3         22
>> >> > > ....    ......      .....
>> >> > > 2000    12       26
>> >> > > 2001     1       27
>> >> > > .......         ........
>> >> > > 2018    11       30
>> >> > > 20118   12      29
>> >> > >
>> >> > > Can someone help me in this regard?
>> >> > >
>> >> > > Many thanks in advance.
>> >> >
>> >> > Hi Md,
>> >> > One way is to form a subset of your
>> >> > data, then calculate the means by
>> >> > year:
>> >> >
>> >> > # assume your data is named mddat
>> >> > mddat2<-mddat[mddat$month < 7,]
>> >> > jan2jun<-by(mddat2$value,mddat2$year,mean)
>> >> >
>> >> > Jim
>> >>
>> >> Hi Md,
>> >>
>> >> you can also define the period in a new
>> >> column, and use aggregate like this:
>> >>
>> >>         Md <- structure(list(
>> >>         Year = c(2000L, 2000L, 2000L,
>> >>         2000L, 2001L, 2018L, 2018L),
>> >>         Month = c(1L, 2L, 3L, 12L, 1L,
>> >>         11L, 12L),
>> >>         Value = c(25L, 28L, 22L, 26L,
>> >>         27L, 30L, 29L)),
>> >>         class = "data.frame",
>> >>         row.names = c(NA, -7L))
>> >>
>> >>         Md[Md$Month %in%
>> >>                 1:6,"Period"] <- "first six months of the year"
>> >>         Md[Md$Month %in% 7:12,"Period"] <- "last six months of the year"
>> >>
>> >>         aggregate(
>> >>           formula=Value~Year+Period,
>> >>           data=Md,
>> >>           FUN=mean)
>> >>
>> >> Rasmus
>> >
>> >
>> >
>
>
>