Re: [R] rownames in an apply function

From: Santosh Srinivas <santosh.srinivas_at_gmail.com>
Date: Tue, 19 Apr 2011 17:21:43 +0530

Thanks.

On Tue, Apr 19, 2011 at 5:16 PM, Gabor Grothendieck <ggrothendieck_at_gmail.com> wrote:

> On Tue, Apr 19, 2011 at 6:59 AM, santosh <santosh.srinivas_at_gmail.com> wrote:

>> Dear Group,
>>
>> I am doing an apply function on a zoo object. I need the rownames to
>> be passed to the function.
>> Any suggestions on how to accomplish this?
>>
>> Here is the code I am using
>>
>> tmp <-
>> structure(c(611.55, 611.55, 611.55, 611.55, 611.55, 520, 520,
>> 520, 520, 520, 425, 425, 425, 432.2, 432.2, 337, 338, 328.95,
>> 328.95, 328.95, 243.8, 242.775, 238.5, 239, 235.925, 161.7, 156.625,
>> 152.825, 151.95, 151.9, 1.5, 1.5, 1.5, 1.5, 1.5, 2, 2.15, 2.15,
>> 2, 2, 3, 2.95, 3.175, 3.2, 3.15, 6, 6.15, 6.525, 6.6, 6.6, 14.5,
>> 14.5, 15.15, 15.45, 15.3, 32.05, 32.05, 33.09, 33.8, 33.23), .Dim =
>> c(5L,
>> 12L), .Dimnames = list(c("2011-04-19 09:24:30", "2011-04-19
>> 09:25:00",
>> "2011-04-19 09:25:30", "2011-04-19 09:26:00", "2011-04-19 09:26:30"
>> ), c("A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L"
>> )), index = structure(c(1303185270, 1303185300, 1303185330,
>> 1303185360,
>> 1303185390), class = c("POSIXt", "POSIXct"), tzone = ""), class =
>> "zoo")
>>
>>
>>> tmp
>>                      A   B   C   D   E   F   G    H    I    J    K
>> L
>> 2011-04-19 09:24:30 612 520 425 337 244 162 1.5 2.00 3.00 6.00 14.5
>> 32.0
>> 2011-04-19 09:25:00 612 520 425 338 243 157 1.5 2.15 2.95 6.15 14.5
>> 32.0
>> 2011-04-19 09:25:30 612 520 425 329 238 153 1.5 2.15 3.17 6.53 15.2
>> 33.1
>> 2011-04-19 09:26:00 612 520 432 329 239 152 1.5 2.00 3.20 6.60 15.4
>> 33.8
>> 2011-04-19 09:26:30 612 520 432 329 236 152 1.5 2.00 3.15 6.60 15.3
>> 33.2
>>
>>> apply(tmp,1,function(x)(print (rownames(x))))
>> NULL
>> NULL
>> NULL
>> NULL
>> NULL
>> NULL
>>>#How can I get the rownames here instead?
>
> Try this:
>
> sapply(time(tmp), function(tt) rownames(tmp[tt]))
>
> # however, it may be that what you really want is
> # the times and not the rownames:
>
> lapply(time(tmp), function(tt) tt)
>
> # also note that indexing by time works
>
> sapply(time(tmp), function(tt) tmp[tt])
>
> --
> Statistics & Software Consulting
> GKX Group, GKX Associates Inc.
> tel: 1-877-GKX-GROUP
> email: ggrothendieck at gmail.com
>

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