apply
Even if this is not a homework question, it smells like one. If you read the Posting Guide it warns you that homework is off-topic, so when you impose an arbitrary constraint like "must use specific unrelated function" we feel like you are either cheating or wasting our time, and it is up to you to explain why we should follow you down this rabbit hole, keeping in mind that statistics theory per-se is also off-topic here. You have yet to explain why you want to do this the hard way.
On October 4, 2024 2:13:26 AM PDT, Steven Yen <syen04 at gmail.com> wrote:
Pardon me!!! What makes you think this is a homework question? You are not obligated to respond if the question is not intelligent enough for you. I did the following: two ways to calculate a covariance matrix but wonder how I might replicate the results with "apply". I am not too comfortable with the online do of apply.
set.seed(122345671) > n<-3 > x<-rnorm(n); x [1] 0.92098449 0.80940115
0.60374785 > cov1<-outer(x-mean(x),x-mean(x))/(n-1); cov1 [,1] [,2] [,3] [1,] 0.0102159207 0.00224105983 -0.0124569805 [2,] 0.0022410598 0.00049161983 -0.0027326797 [3,] -0.0124569805 -0.00273267965 0.0151896601 > cov2<-(x-mean(x))%*%t((x-mean(x)))/(n-1); cov2 [,1] [,2] [,3] [1,] 0.0102159207 0.00224105983 -0.0124569805 [2,] 0.0022410598 0.00049161983 -0.0027326797 [3,] -0.0124569805 -0.00273267965 0.0151896601 > On 10/4/2024 4:57 PM, Uwe Ligges wrote:
Homework questions are not answered on this list. Best, Uwe Ligges On 04.10.2024 10:32, Steven Yen wrote:
The following line calculates standard deviations of a column vector: se<-apply(dd,1,sd) How can I calculate the covariance matrix using apply? Thanks.
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______________________________________________ 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 https://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
Sent from my phone. Please excuse my brevity.