aggregate semi-hourly data not 00-24 but 9-9
Hi Stefano,
If you mean from 9am on one day to 9am on the following day, you can
do a trick. Simply subtract 9hrs from each timestamp and then you want
midnight to midnight for these adjusted times, which you can get using
the method you followed.
I googled and found that lubridate::hours() can be used to add or
subtract hours from a POSIXct.
library(lubridate)
day_1 <- as.POSIXct("2020-02-19-00-00", format="%Y-%m-%d-%H-%M", tz="Etc/GMT-1")
day_2 <- as.POSIXct("2020-02-24-12-00", format="%Y-%m-%d-%H-%M", tz="Etc/GMT-1")
df1 <- data.frame(data_POSIX=seq(day_1, day_2, by="30 min"))
df1$hs <- rnorm(nrow(df1), 40, 10)
df1$diff[2:nrow(df1)] <- diff(df1$hs)
df1$data_POSIXminus9 <- df1$data_POSIX - lubridate::hours(9)
df1$dayX <- format(df1$data_POSIXminus9,"%y-%m-%d")
df2X <- aggregate(diff ~ dayX, df1, sum)
df2X
HTH,
Eric
On Mon, Sep 21, 2020 at 5:30 PM Stefano Sofia
<stefano.sofia at regione.marche.it> wrote:
Dear R-list members,
I have semi-hourly snowfall data.
I should sum the semi-hourly increments (only the positive ones, but this is not described in my example) day by day, not from 00 to 24 but from 9 to 9.
I am able to use the diff function, create a list of days and use the function aggregate, but it works only from 0 to 24. Any suggestion for an efficient way to do it?
Here my code:
day_1 <- as.POSIXct("2020-02-19-00-00", format="%Y-%m-%d-%H-%M", tz="Etc/GMT-1")
day_2 <- as.POSIXct("2020-02-24-12-00", format="%Y-%m-%d-%H-%M", tz="Etc/GMT-1")
df1 <- data.frame(data_POSIX=seq(day_1, day_2, by="30 min"))
df1$hs <- rnorm(nrows(df1), 40, 10)
df1$diff[2:nrow(df1)] <- diff(df1$hs)
df1$day <- format(df$data_POSIX,"%y-%m-%d")
df2 <- aggregate(diff ~ day, df, sum)
Thank you for your help
Stefano
(oo)
--oOO--( )--OOo----------------
Stefano Sofia PhD
Civil Protection - Marche Region
Meteo Section
Snow Section
Via del Colle Ameno 5
60126 Torrette di Ancona, Ancona
Uff: 071 806 7743
E-mail: stefano.sofia at regione.marche.it
---Oo---------oO----------------
________________________________
AVVISO IMPORTANTE: Questo messaggio di posta elettronica pu? contenere informazioni confidenziali, pertanto ? destinato solo a persone autorizzate alla ricezione. I messaggi di posta elettronica per i client di Regione Marche possono contenere informazioni confidenziali e con privilegi legali. Se non si ? il destinatario specificato, non leggere, copiare, inoltrare o archiviare questo messaggio. Se si ? ricevuto questo messaggio per errore, inoltrarlo al mittente ed eliminarlo completamente dal sistema del proprio computer. Ai sensi dell?art. 6 della DGR n. 1394/2008 si segnala che, in caso di necessit? ed urgenza, la risposta al presente messaggio di posta elettronica pu? essere visionata da persone estranee al destinatario.
IMPORTANT NOTICE: This e-mail message is intended to be received only by persons entitled to receive the confidential information it may contain. E-mail messages to clients of Regione Marche may contain information that is confidential and legally privileged. Please do not read, copy, forward, or store this message unless you are an intended recipient of it. If you have received this message in error, please forward it to the sender and delete it completely from your computer system.
--
Questo messaggio stato analizzato da Libra ESVA ed risultato non infetto.
This message was scanned by Libra ESVA and is believed to be clean.
[[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.