[R] How to use apply() to fill matrix by rows or columns?

[C W]

I suppose for loop will suffice.

I simply copy & paste the code from R editor. From my email, it looks
plain. Is there a way to tell?

On Fri, Feb 24, 2017 at 8:50 PM, Jeff Newmiller <jdnewmil at dcn.davis.ca.us>
wrote:

> The apply function is one of many alienate ways to write a loop. It is not
> appreciably more efficient in cpu time than a for loop.
>
> Your example creates the numbers in the loop... does your actual data get
> created in a loop? If so then your original code should be perfectly
> serviceable. If not then there might be a better way to do this, but you
> would have to expand your example to illustrate how the data comes to you
> in order to suggest alternatives.
>
> Also post using plain text to prevent your code from being mangled on its
> way to us.
> --
> Sent from my phone. Please excuse my brevity.
>
> On February 24, 2017 5:27:07 PM PST, C W <tmrsg11 at gmail.com> wrote:
> >In theory, I am generating from group 5 groups of random numbers, each
> >group has 3 samples.
> >
> >Isn't apply() the replacement of loops?
> >
> >On Fri, Feb 24, 2017 at 8:23 PM, Jeff Newmiller
> ><jdnewmil at dcn.davis.ca.us>
> >wrote:
> >
> >> What is wrong with
> >>
> >> dat <- matrix(rnorm(15), nrow=5, ncol = 3)
> >>
> >> ?
> >>
> >> And what is this "no loop drama" you refer to? I use loops frequently
> >to
> >> loop around large memory gobbling chunks of code.
> >>
> >> --
> >> Sent from my phone. Please excuse my brevity.
> >>
> >> On February 24, 2017 5:02:46 PM PST, C W <tmrsg11 at gmail.com> wrote:
> >> >Dear R,
> >> >
> >> >I wanted to simulate a 5 by 3 matrix which fills up by either rows
> >or
> >> >columns?
> >> >
> >> >I started with the following filling the matrix by rows,
> >> >
> >> >dat <- matrix(NA, nrow=5, ncol = 3)
> >> >
> >> >for(i in 1:5){
> >> >
> >> >    dat[i, ] <- rnorm(3)
> >> >
> >> >}
> >> >
> >> >But, R is known for no loop drama. Any suggestions?
> >> >
> >> >Thanks!
> >> >
> >> >       [[alternative HTML version deleted]]
> >> >
> >> >______________________________________________
> >> >R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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> >> >PLEASE do read the posting guide
> >> >http://www.R-project.org/posting-guide.html
> >> >and provide commented, minimal, self-contained, reproducible code.
> >>
>

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