Jeff Newmiller
Sent: Monday, July 18, 2022 12:35 AM
To: Greg Comcast Coats ; Gregory Coats via R-help
Subject: Re: [R] Date and Time
[External Email]
Maybe this [1] will help? Or just read ?strptime...
You can also calculate sunrise/sunset (crepuscule) using maptools, but you need
to be careful
On 7/17/2022 8:47 PM, Gregory Coats via R-help wrote:
For the year from 2022-01-01 to 2022-12-31, I computed the sunrise and sunset
times for Reston, Virginia, USA. I am seeking the syntax to direct R to read in
these dates and times, and then graphical plot the sunrise and sunset times for
ea
Maybe this [1] will help? Or just read ?strptime...
You can also calculate sunrise/sunset (crepuscule) using maptools, but you need
to be careful with timezones.
[1] https://jdnewmil.github.io/time-2018-10/MoreDatetimeHowto.html
On July 17, 2022 8:47:19 PM PDT, Gregory Coats via R-help
wrote:
Hi, Bert
I will check those two, by the way, how can you find the two function? have you
used them before?
Thanks very much.
From: Bert Gunter
Date: 2018-11-04 10:07
To: snowball0916
CC: MacQueen, Don; R-help
Subject: Re: [R] date and time data on x axis
See ?identify and ?locator
Cheers
e other way to get the same goal?
>
> Thanks very much.
>
>
>
>
>
> From: MacQueen, Don
> Date: 2018-10-30 00:01
> To: snowball0916; r-help
> Subject: Re: [R] date and time data on x axis
> Here's an example of 24 hours of data at one second intervals.
>
&g
hanks very much.
From: MacQueen, Don
Date: 2018-10-30 00:01
To: snowball0916; r-help
Subject: Re: [R] date and time data on x axis
Here's an example of 24 hours of data at one second intervals.
npts <- 24*60*60
df <- data.frame(
tm = seq( Sys.time(), by
Hi, Don
I got it, I will try and study .
Thanks very much.
From: MacQueen, Don
Date: 2018-10-30 00:01
To: snowball0916; r-help
Subject: Re: [R] date and time data on x axis
Here's an example of 24 hours of data at one second intervals.
npts <- 24*60*60
df <-
Hi, Rui
Thank you . I will try later.
Thanks again.
From: Rui Barradas
Date: 2018-10-30 00:38
To: snowball0916; r-help
Subject: Re: [R] date and time data on x axis
Hello,
Inline.
Às 14:03 de 29/10/2018, snowball0916 escreveu:
> Hi, Rui
> Thanks for your code, even though I
*From:* Rui Barradas <mailto:ruipbarra...@sapo.pt>
*Date:* 2018-10-29 02:53
*To:* snowball0916 <mailto:snowball0...@163.com>; r-help
<mailto:r-help@r-project.org>
*Subject:* Re: [R] date and time data on x axis
Hello,
Maybe y
Here's an example of 24 hours of data at one second intervals.
npts <- 24*60*60
df <- data.frame(
tm = seq( Sys.time(), by='1 sec', length=npts),
yd = round(runif(npts),2)
)
head(df)
with(df, plot(tm,yd))
The x axis appears to me to be display
Hi, Jim
Thanks very much, I will need to study your code, though.
Will large volume of data will affect the x axis display?
Thanks again.
From: jim holtman
Date: 2018-10-29 05:53
To: snowball0916
CC: R mailing list
Subject: Re: [R] date and time data on x axis
You need to specify what the
d help(POSIXct) and not found the actual use.
Thanks very much.
From: Rui Barradas
Date: 2018-10-29 02:53
To: snowball0916; r-help
Subject: Re: [R] date and time data on x axis
Hello,
Maybe you could get some inspiration in the following code.
op <- par(mar = c(4, 0, 0, 0) + par(&
You need to specify what the format of the date will be. I am using
ggplot for the plot:
library(lubridate)
library(tidyverse)
mydata <- read.table(text = "time value
20181028_10:00:00 600
20181028_10:00:01 500
20181028_10:00:02 450
20181028_10:00:03 660", header = TR
Hello,
Maybe you could get some inspiration in the following code.
op <- par(mar = c(4, 0, 0, 0) + par("mar"))
plot(xdata, ydata, type = "o", xaxt = "n")
axis.POSIXct(1, xdata, at = xdata, labels = xdata, las = 2)
par(op)
The important part is the call axis.POSIXct, argument las = 2 and the
I stand by my previous statement: you should avoid thinking of difftime objects
as having units. At the point when you learn to regard the units argument as
being associated with the numeric values you pass TO as.difftime or that you
extract FROM a difftime object with as.numeric, then you will
,], points(day, as.numeric(alarm-sunrise, units="mins"),
cex=2.5, pch=1, col="orange"))
Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com
> -Original Message-
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On
> Behalf
> Of Jeff N
The difftime() function has a units argument, so it seems kind of obvious
to me to think of objects of class 'difftime' as having units. And indeed
they do, stored as an attribute:
> str(difftime( Sys.time()+3700, Sys.time(), units='min'))
Class 'difftime' atomic [1:1] 61.7
..- attr(*, "units")
The difference of two POSIXct values is of type difftime. You should not think
of difftime as having units. Rather, you should think of the result of
converting from difftime to numeric (using as.numeric) as the opportunity (or
rather requirement) to specify what time units you want. If you let
I think you probably want
format='%m/%d/%y %H:%M')
(lower case "y")
diff() as suggested by Jeff Newmiller is good, except that I don't know
how to control the units using diff().
## so a method that allows specifying units other than hours would be, for
example,
datetime <-c("1/1/13 00:00","
a) Please read the Posting Guide and post in plain text as it says to do. This
is an adjustment you must make in your email client software, we cannot advise
you how to do it here.
b) Not clear why you want a matrix. A vector is more typical in R; most of the
time using n*1 matrices is an unnec
Hello,
mpostje wrote
>
> Hi
>
> I've been trying to convert numbers from an online temperature database
> into dates and time that R recognizes. the problem is that the database
> has put a T
> between the numbers and R will not accept any conversions.
>
> this is the format that it's in now
Quick and dirty solution is to use sub() to change the T to a space
and then use as.POSIXct as usual.
x <- "1981-01-02T08:00"
as.POSIXct(sub("T"," ", x), format = "%Y-%m-%d %H:%M")
but it does look to me like R can work around the T if you give a good
format argument:
as.POSIXct(x, format = "%Y
Good afternoon Robert,
Suppose you have your date and time in characters like this:
d.start = "2008-04-11"
t.start = "22:00:00"
d.end = "2008-04-12"
t.end = "15:00:00"
then use POSIXct to convert them to a unified time object:
start <- as.POSIXct(paste(d.start, t.start))
end <- as.POSIXct(past
Read the article in R News 4/1.
2010/1/27 Robert Kalicki :
> Dear R community
>
> I would like to perform some statistical analysis on a data set containing
> the following items: date, time, index of observation and various
> covariates.
>
> The date and time are originally extracted in the follo
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