[R] Get data from a list of data frames (Stefano Sofia)

[Bert Gunter]

... and note that my previous version can be simplified using R's pipe
syntax to:

do.call('rbind',Total[select.stat]) |>
   subset(sensor == 'thermometer', code)

## which calls the subset.data.frame() method that gives:
                 code
Station1.1 2583
Station4.4 4453
Station5.3 3179

close to the form that you suggested.
Same caveats as my previous post.

Cheers,
Bert


On Fri, Dec 16, 2022 at 7:16 AM Jorgen Harmse via R-help <
r-help using r-project.org> wrote:

> Following Bert Gunter's suggestion, I wonder why the data are in separate
> frames (with hard-coded values) in the first place. You could put them in a
> text file and call read.table. If you provide a header and put a meaningful
> station name at the start of each data row then rownames of your data frame
> will be meaningful.
>
> Regards,
> Jorgen Harmse.
>
> From: R-help <r-help-bounces using r-project.org> on behalf of
> r-help-request using r-project.org <r-help-request using r-project.org>
> Date: Friday, 16December, 2022 at 05:00
> To: r-help using r-project.org <r-help using r-project.org>
> Subject: [EXTERNAL] R-help Digest, Vol 238, Issue 16
>
> Message: 1
> Date: Thu, 15 Dec 2022 13:52:35 +0000
> From: Stefano Sofia <stefano.sofia using regione.marche.it>
> To: "r-help using R-project.org" <r-help using R-project.org>
> Subject: [R] Get data from a list of data frames
> Message-ID: <fe9017cbd4ba49328e150061032068a7 using regione.marche.it>
> Content-Type: text/plain; charset="utf-8"
>
> Dear R-list users,
>
> I have a list of n data frames built as follows:
>
>
> Station1 <- data.frame(sensor = c("thermometer", "raingauge", "snowgauge",
> "anemometer"), code = c(2583, 1478, 3178, NA))
> Station2 <- data.frame(sensor = c("thermometer", "raingauge", "snowgauge",
> "anemometer"), code = c(2584, 1479, 3179, 4453))
> ....
>
> Total <- list("Station1"=Station1, "Station2"=Station2, ...)
>
> I would need to have a vector with the sensor codes of the thermometers of
> some stations, let's say of Station1, Station2 and Station5 (i.e. c(2583,
> 2584, 2587)).
> I tried with lapply, but I have not been able to get what I need.
> Could you please help me?
>
> Thank you
>
> Stefano
>
>
>
>          (oo)
> --oOO--( )--OOo--------------------------------------
> Stefano Sofia PhD
> Civil Protection - Marche Region - Italy
> Meteo Section
> Snow Section
> Via del Colle Ameno 5
> 60126 Torrette di Ancona, Ancona (AN)
> Uff: +39 071 806 7743
> E-mail: stefano.sofia using regione.marche.it
> ---Oo---------oO----------------------------------------
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> ------------------------------
>
> Message: 4
> Date: Thu, 15 Dec 2022 09:31:51 -0800
> From: Bert Gunter <bgunter.4567 using gmail.com>
> To: Gerrit Eichner <gerrit.eichner using math.uni-giessen.de>,
>         stefano.sofia using regione.marche.it
> Cc: r-help using r-project.org
> Subject: Re: [R] Get data from a list of data frames
> Message-ID:
>         <
> CAGxFJbTgwQ2Nop0bjCzcT7Ri6FhDmOrXiXv+o2-2m_-sqZ6H_w using mail.gmail.com>
> Content-Type: text/plain; charset="utf-8"
>
> Well, just for giggles, Gerrit's solution can be easily vectorized (i.e. no
> apply()-type stuff needed) IFF the structure of all the data frames are
> identical so that rbind() works:
>
> d <-do.call('rbind',Total[select.stat]) ## one data frame to combine them
> all ;-)
> d[d$sensor == 'thermometer','code']
>
> Whether this is better, worse, or unneeded, I cannot say.
>
> Cheers,
> Bert
>
>
>
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>
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