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

Fri, Feb 24, 2017 6:16 PM

There is a little button near the bottom of the Gmail editing box that switches to plain text. We can immediately tell because of the


line when we receive it, and sometimes it loses all of the line breaks or has extra asterisks mixed in. You can look in the archives or replies to see what we see.

Sent from my phone. Please excuse my brevity.

On February 24, 2017 5:55:15 PM PST, C W <tmrsg11 at gmail.com> wrote:
>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
>> >> >https://stat.ethz.ch/mailman/listinfo/r-help
>> >> >PLEASE do read the posting guide
>> >> >http://www.R-project.org/posting-guide.html
>> >> >and provide commented, minimal, self-contained, reproducible
>code.
>> >>
>>

Thread (9 messages)

C W How to use apply() to fill matrix by rows or columns? Feb 24 Jeff Newmiller How to use apply() to fill matrix by rows or columns? Feb 24 C W How to use apply() to fill matrix by rows or columns? Feb 24 Jeff Newmiller How to use apply() to fill matrix by rows or columns? Feb 24 C W How to use apply() to fill matrix by rows or columns? Feb 24 Jeff Newmiller How to use apply() to fill matrix by rows or columns? Feb 24 C W How to use apply() to fill matrix by rows or columns? Feb 24 Jeff Newmiller How to use apply() to fill matrix by rows or columns? Feb 24 C W How to use apply() to fill matrix by rows or columns? Feb 24