[R] Applying a certain formula to a repeated sample data

[Ogbos Okike]

Dear Jim,

I wish also to use the means calculated and apply a certain formula on the
same data frame. In particular, I would like to subtract the means of each
of these seven days from each of the seven days and and divide the outcome
by the same means. If I represent m1 by the means of each seven days in
column 1, and c1 is taken as column 1 data. My formula will be of the form:
aa<-(c1-m1)/m1.

I tried it on the first 7 rows and I have what I am looking for.:
 -0.0089986156
  -0.0031149054
   0.0042685741
   0.0094600831
   0.0019612367
  -0.0044993078
   0.0009229349

But doing it manually will take much time.

Many thanks for going a step further to assist me.

Warmest regards.
Ogbos

On Wed, Nov 28, 2018 at 4:31 AM Jim Lemon <drjimlemon using gmail.com> wrote:

> Hi Ogbos,
> If we assume that you have a 3 column data frame named oodf, how about:
>
> oodf[,4]<-floor((cumsum(oodf[,1])-1)/28)
> col2means<-by(oodf[,2],oodf[,4],mean)
> col3means<-by(oodf[,3],oodf[,4],mean)
>
> Jim
>
> On Wed, Nov 28, 2018 at 2:06 PM Ogbos Okike <giftedlife2014 using gmail.com>
> wrote:
> >
> > Dear List,
> > I have three data-column data. The data is of the form:
> > 1 8590 12516
> > 2 8641 98143
> > 3 8705 98916
> > 4 8750 89911
> > 5 8685 104835
> > 6 8629 121963
> > 7 8676 77655
> > 1 8577 81081
> > 2 8593 83385
> > 3 8642 112164
> > 4 8708 103684
> > 5 8622 83982
> > 6 8593 75944
> > 7 8600 97036
> > 1 8650 104911
> > 2 8730 114098
> > 3 8731 99421
> > 4 8715 85707
> > 5 8717 81273
> > 6 8739 106462
> > 7 8684 110635
> > 1 8713 105214
> > 2 8771 92456
> > 3 8759 109270
> > 4 8762 99150
> > 5 8730 77306
> > 6 8780 86324
> > 7 8804 90214
> > 1 8797 99894
> > 2 8863 95177
> > 3 8873 95910
> > 4 8827 108511
> > 5 8806 115636
> > 6 8869 85542
> > 7 8854 111018
> > 1 8571 93247
> > 2 8533 85105
> > 3 8553 114725
> > 4 8561 122195
> > 5 8532 100945
> > 6 8560 108552
> > 7 8634 108707
> > 1 8646 117420
> > 2 8633 113823
> > 3 8680 82763
> > 4 8765 121072
> > 5 8756 89835
> > 6 8750 104578
> > 7 8790 88429
> >
> > I wish to calculate average of the second and third columns based on the
> > first column for each repeated 7 days. The length of the data is 1442.
> That
> > is 206 by 7. So I should arrive at 207 data points for each of the two
> > columns after calculating the mean of each group 1-7.
> >
> > I have both tried factor/tapply and aggregate functions but seem not to
> be
> > making progress.
> >
> > Thank you very much for your idea.
> >
> > Best wishes
> > Ogbos
> >
> >         [[alternative HTML version deleted]]
> >
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>

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