[R] date and time data on x axis

[snowball0916]

Hi, Rui
Thanks for your code, even though I'm not fully understand it.
And I am new to R, could you kindly help me with
-1). what's the nested usage stand for?
op <- par(mar = c(4, 0, 0, 0) + par("mar"))

-2). how can I get the axis.POSIXct usage or help?
I use help(axis) and 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("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 
call to par is to make sure that the labels are visible.
 
 
Hope this helps,
 
Rui Barradas
 
 
Às 15:16 de 28/10/2018, snowball0916 escreveu:
> Hi, guys
> How do you guys deal with the date and time data on x axis?
> I have some trouble with it. Could you help with this?
> 
> =============
> Sample Data
> =============
> The sample data look like this:
> 
> 20181028_10:00:00 600
> 20181028_10:00:01 500
> 20181028_10:00:02 450
> 20181028_10:00:03 660
> ......
> 
> =============
> My Code
> =============
> 
> library(lubridate)
> mydata <- read.table("e:/R_study/graph_test2.txt")
> xdata <- ymd_hms(mydata$V1)
> ydata <- mydata$V2
> plot(xdata, ydata, type="o")
> 
> 
> =============
> Questions:
> =============
> 
> 1. Why my x axis does not show me the correct date time like ""2018-10-28 10:00:00 UTC" ?
> 2. If my data is very huge(like data in every second and the data has the whole day , even the whole month), how can I display the x axis in a neat and clean way?
> 
> Thanks very much.
>   
> 
> 
> 
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