# [R] Occurrence by season

Bert Gunter bgunter@4567 @end|ng |rom gm@||@com
Wed Apr 21 20:36:26 CEST 2021

```Simpler, and no loops needed per column:
## this makes the idea clear
> x <- 1:12
> (x %% 12) %/% 3 ## first modulo, then integer divide
[1] 0 0 1 1 1 2 2 2 3 3 3 0

## add 1 if you prefer 1 to 4. Better yet, probably, is to turn it into a
factor:
> f <- factor(c("win","spr","sum","fal")[x+1])
> f
[1] win win spr spr spr sum sum sum fal fal fal win
Levels: fal spr sum win

## see ?factor if you want to alter the ordering of the levels (e.g. for
graphics, nice tables of results, etc.)

Cheers,

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )

On Wed, Apr 21, 2021 at 1:48 AM Eric Berger <ericjberger using gmail.com> wrote:

> Hi Ani,
> Before the for loops add the following line
>
> when[,-1] <- when[,-1]%%12 + 1
>
> This changes the month numbering so that Dec becomes 1, Jan becomes 2, etc
> Then your for loop does what you want.
>
> HTH,
> Eric
>
>
>
>
> On Wed, Apr 21, 2021 at 11:09 AM ani jaya <gaaauul using gmail.com> wrote:
>
> > Dear r community,
> >
> > I have a data frame that shows the month of occurrence of the maximum
> > value on let say 10 stations in 30 years.  I want to make percentages
> > based on seasons (DJF, MAM, JJA, and SON). I can do that by the code
> > below but only when we put season by JFM, AMJ, ...(or 123; 456;
> > 789;..).
> > I believe it is not that hard to put 12 in front of 1 but my mind stuck.
> >
> > If someone can help me, I would be appreciated.
> >
> > Thank you in advance
> >
> > Ani
> >
> >
> > freqw<-matrix(NA, 4,10)
> > for(j in 1:4){
> >   for(i in 1:10){
> >       freqw[j,i]<-sum(table(when[i+1])[(j*3-2):(j*3)],na.rm=T)
> >   }
> > }
> > freqw<-freqw/30*100
> >
> >
> > > dput(when)
> > structure(list(Group.1 = structure(1:30, .Label = c("1985", "1986",
> > "1987", "1988", "1989", "1990", "1991", "1992", "1993", "1994",
> > "1995", "1996", "1997", "1998", "1999", "2000", "2001", "2002",
> > "2003", "2004", "2005", "2006", "2007", "2008", "2009", "2010",
> > "2011", "2012", "2013", "2014"), class = "factor"), V1 = c(8L,
> > 1L, 1L, 12L, 12L, 1L, 4L, 1L, 2L, 3L, 7L, 4L, 1L, 6L, 2L, 2L,
> > 11L, 4L, 2L, 2L, 12L, 6L, 2L, 2L, 6L, 3L, 6L, 4L, 7L, 1L), V2 = c(1L,
> > 1L, 1L, 1L, 12L, 12L, 4L, 1L, 2L, 2L, 4L, 1L, 11L, 1L, 1L, 3L,
> > 3L, 1L, 12L, 2L, 5L, 2L, 12L, 2L, 1L, 5L, 10L, 4L, 12L, 1L),
> >     V3 = c(4L, 1L, 12L, 12L, 2L, 4L, 1L, 5L, 1L, 1L, 2L, 2L,
> >     1L, 1L, 2L, 2L, 4L, 1L, 2L, 12L, 3L, 2L, 12L, 4L, 6L, 4L,
> >     2L, 3L, 5L, 1L), V4 = c(1L, 12L, 12L, 3L, 2L, 12L, 7L, 2L,
> >     12L, 1L, 12L, 2L, 1L, 12L, 1L, 10L, 7L, 1L, 1L, 3L, 10L,
> >     12L, 12L, 12L, 5L, 12L, 3L, 2L, 12L, 1L), V5 = c(1L, 12L,
> >     12L, 3L, 2L, 12L, 7L, 2L, 12L, 3L, 4L, 12L, 5L, 2L, 1L, 1L,
> >     2L, 5L, 2L, 2L, 3L, 2L, 10L, 3L, 1L, 1L, 4L, 1L, 4L, 6L),
> >     V6 = c(12L, 1L, 12L, 2L, 1L, 12L, 3L, 1L, 4L, 12L, 6L, 12L,
> >     1L, 7L, 2L, 2L, 1L, 1L, 12L, 12L, 12L, 3L, 12L, 2L, 1L, 9L,
> >     12L, 1L, 4L, 12L), V7 = c(5L, 2L, 6L, 12L, 3L, 4L, 12L, 12L,
> >     6L, 2L, 11L, 12L, 2L, 5L, 11L, 4L, 3L, 4L, 1L, 12L, 10L,
> >     3L, 10L, 3L, 3L, 9L, 1L, 3L, 12L, 11L), V8 = c(4L, 5L, 5L,
> >     8L, 7L, 12L, 1L, 3L, 2L, 5L, 2L, 4L, 1L, 4L, 1L, 6L, 6L,
> >     2L, 3L, 5L, 4L, 1L, 3L, 12L, 4L, 12L, 12L, 3L, 6L, 7L), V9 = c(3L,
> >     2L, 3L, 11L, 7L, 2L, 4L, 4L, 5L, 6L, 6L, 3L, 4L, 6L, 1L,
> >     9L, 9L, 12L, 3L, 12L, 5L, 6L, 3L, 7L, 4L, 8L, 2L, 2L, 6L,
> >     6L), V10 = c(5L, 10L, 3L, 6L, 6L, 5L, 5L, 6L, 5L, 6L, 12L,
> >     6L, 7L, 2L, 1L, 6L, 4L, 5L, 4L, 2L, 7L, 6L, 7L, 7L, 2L, 7L,
> >     3L, 6L, 7L, 6L)), row.names = c(NA, -30L), class = "data.frame")
> >
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