Example is not equivalent

[nacnudus]

Yet the above lengthy R code can be done much more compactly. E.g

with(mtcars,tapply(mpg,list(cyl,gear),function(x) c(mean(x),sd(x)))

with output

     3      4    5
4 21.50 26.925 28.2
6 19.75 19.750 19.7
8 15.05     NA 15.4

Not only is the code highly compact, but also the output is nicer, in
table form.

This is not equivalent in an important way: the table form is difficult to use in subsequent commands. For example, try filtering the table for the combination of cyl and mpg that has the highest mean mpg.

[nacnudus]

Also it doesn't render the quoted output.

with(mtcars,tapply(mpg,list(cyl,gear),function(x) c(mean(x),sd(x))))
#>   3         4         5
#> 4 Numeric,2 Numeric,2 Numeric,2
#> 6 Numeric,2 Numeric,2 Numeric,2
#> 8 Numeric,2 NULL      Numeric,2

Your output seems to the be result of applying only mean() and not sd().

with(mtcars,tapply(mpg,list(cyl,gear),function(x) c(mean(x))))
#>       3      4    5
#> 4 21.50 26.925 28.2
#> 6 19.75 19.750 19.7
#> 8 15.05     NA 15.4

[matloff]

If one assigns the result to z, then which.max(z) does work. However, it gives 7, saying the 7th element is the largest, which may not be so convenient. I assume there is a table helper function to deal with this, but I'm not deep enough into tables to say.

As to displaying only the means, that's of course why I wrote "E.g." One could do 3 with() calls, or use tapply() with a custom function.

[nacnudus]

As to displaying only the means, my point is that

with(mtcars,tapply(mpg,list(cyl,gear),function(x) c(mean(x),sd(x)))

does not output

     3      4    5
4 21.50 26.925 28.2
6 19.75 19.750 19.7
8 15.05     NA 15.4

[matloff]

Thanks! Wrote this on my phone, traveling on a train. Norm

…

On Mon, Jul 15, 2019 at 03:23:25PM -0700, Duncan Garmonsway wrote: As to displaying only the means, my point is that ``` r with(mtcars,tapply(mpg,list(cyl,gear),function(x) c(mean(x),sd(x))) ``` does not output ``` r 3 4 5 4 21.50 26.925 28.2 6 19.75 19.750 19.7 8 15.05 NA 15.4 ``` -- You are receiving this because you commented. Reply to this email directly or view it on GitHub: #15 (comment)