On Jan 13, 2012, at 10:45 AM, statquant2 wrote:
Hello,
I have a data.frame and I want to transfor it in a list of rows or
columns.
I can do apply(myDataFrame,MARGIN=1,FUN=???)
I remember that there is a function which mean return or access
column ...
something like "::" or "]," or "[,"
I can't remember can somebody refresh my memory?
It is definitely "the long way around) to do this, since [,5] would
get the same results, but if you want the fifth element in each row
you could do this:
> dat
id x1 x2 x3 y1 y2 y3 z1 z2 z3 v
1 1 2 4 5 10 20 15 200 150 170 2.5
2 2 3 7 6 25 35 40 300 350 400 4.2
> apply(dat, 1, "[", 5)
[1] 10 25
When 'apply' is used, the trailing arguments are matched either by
position or name to the arguments of the function. In this case the 5
gets matched to the "i" for the "[" function. Because "[" is primitive
the name is actually ignored even if offered, so using any other name
would not change the result:
> apply(dat, 1, "[", j=5)
[1] 10 25
Whereas if you were using quantile as your function, you might perhaps
use prob=c(,25,,75), na.rm=TRUE or na.rm=TRUE prob=c(,25,,75), prob=c(,
25,,75)
--
David Winsemius, MD
West Hartford, CT
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