[R] Plotting wind direction as arrows with precipitation

Tue Aug 11 18:52:32 CEST 2015

Thanks Bert,
I think that arrow()  would do what the OP needs. The main problem would be calculating the angles properly if I understand the issue. Still there cannot be "that" many points on a compass, can there?

John Kane
Kingston ON Canada

> -----Original Message-----
> From: bgunter.4567 at gmail.com
> Sent: Tue, 11 Aug 2015 07:55:55 -0700
> To: jrkrideau at inbox.com
> Subject: Re: [R] Plotting wind direction as arrows with precipitation
> 
> ... don't know if this will help, but grid graphics, which is the
> graphics engine for both trellis and ggplot, has a basic arrow()
> function. Trellis's provides an interface to it with the
> panel.arrows() panel function. I suspect ggplot has something similar,
> but as I don't use it, I don't know for sure.
> 
> There is also an arrows() function in the basic (non-grid) graphics
> engine, but this is probably irrelevant for your needs.
> 
> Cheers,
> Bert
> 
> 
> Bert Gunter
> 
> "Data is not information. Information is not knowledge. And knowledge
> is certainly not wisdom."
>    -- Clifford Stoll
> 
> 
> On Tue, Aug 11, 2015 at 7:16 AM, John Kane <jrkrideau at inbox.com> wrote:
>> Hi,
>> Good example and data.  Thanks.
>> 
>> Here are a couple of approaches that may help.
>> I tend to use a lot of what I tend to think of as the ggplot family of
>> associated so you may need to install a couple packages. I used
>> lubridate to transform your character dates to  POSIXct. Jeff N's code
>> does exatly the same in base R. so you don't really need the lubridate
>> package.
>> 
>>  I changed the data set name to dat1 and transformed the column names to
>> lower case just for my convenience.  Data is now in dput() form. See
>> ?dput() for more information. It is the preferred way to share data on
>> R-help
>> 
>> Given what appears to be vastly different y-scales for rainfall and wind
>> direction it struck me that it might be better to have the data in two
>> plots so I included that option.
>> 
>> I am not really sure how to get the arrows you want. You may be able to
>> do it using scale_shape_manual  but I am not sure if the required
>> symbols are available.
>> 
>> You may have to manually draw them. See
http://stackoverflow.com/questions/3421331/example-needed-using-arrow-with-ggplot2
>> for how to draw an arrow.
>> 
>> John Kane
>> Kingston ON Canada
>> ##============Start code==============
>> library(ggplot2)
>> library(reshape2)
>> library(lubridate)
>> library(gridExtra)
>> 
>> dat1  <-  structure(list(deal1 = c("10/22/2012 0:00", "10/22/2012 0:15",
>> "10/22/2012 0:30", "10/22/2012 0:45", "10/22/2012 1:00", "10/22/2012
>> 1:15"
>> ), rainfall_cm = c(0L, 0L, 0L, 0L, 0L, 0L), wind_direction1 = c(296L,
>> 317L, 323L, 323L, 326L, 326L), wind_direction2 = c("W", "NW",
>> "NW", "NW", "NW", "NW")), .Names = c("deal1", "rainfall_cm",
>> "wind_direction1", "wind_direction2"), class = "data.frame", row.names =
>> c(NA,
>> -6L))
>> 
>> 
>> dat1$deal1 <- mdy_hm(dat1$deal1) # Lazy man's equivalent of Jeff N's
>> Sandy$Deal1 <- as.POSIXct( Sandy$Deal1, format="%m/%d/%Y %H:%M")
>> 
>> dat2  <-  melt(dat1[ , 1:3], id.var = "deal1")  # use reshape to
>> rearrange data.
>> p  <-  ggplot(dat2, aes(deal1, value, colour = variable) )+ geom_point()
>> p
>> 
>> ## possible option
>> g1  <-  ggplot(dat1, aes(deal1,  wind_direction1)) + geom_point() +
>> theme(axis.title.x=element_blank())
>> g2  <-  ggplot(dat1, aes(deal1, rainfall_cm ) )+ geom_point()
>> 
>> grid.arrange( g1, g2, ncol=1)
>> 
>> ##===========end code==================
>> 
>> 
>>> -----Original Message-----
>>> From: rhelp10 at gmail.com
>>> Sent: Mon, 10 Aug 2015 00:05:27 -0400
>>> To: r-help at r-project.org
>>> Subject: [R] Plotting wind direction as arrows with precipitation
>>> 
>>> Hello R users!
>>> 
>>> I am trying to create a time series in R with two variables,
>>> precipitation
>>> and wind direction vs Date/Time.
>>> 
>>> I am looking for suggestions and maybe even sample code.
>>> 
>>> My workbook is called "Sandy" and has columns with Date/Time,
>>> Raindall_cm,
>>> Wind Direction in both degree format (0-359) and in character form (N,
>>> NW,
>>> S, SW, SE, E, NE, NW).
>>> 
>>> I have done some reading for it on stackoverflow and other sites but
>>> not
>>> making head way.
>>> 
>>> I will be graphing with ggplot most likely and am a beginner in R, self
>>> taught from books and online resources.
>>> 
>>> This is the code I have and a small peak into the data.
>>> 
>>> Sandy<-read.csv("Sandy.csv", header=TRUE,
>>> sep=",",stringsAsFactors=FALSE)
>>>> head(Sandy)
>>>       Deal1     Rainfall_cm    Wind_Direction1 Wind_Direction2
>>> 1 10/22/2012 0:00           0        296         W
>>> 2 10/22/2012 0:15           0        317        NW
>>> 3 10/22/2012 0:30           0        323        NW
>>> 4 10/22/2012 0:45           0        323        NW
>>> 5 10/22/2012 1:00           0        326        NW
>>> 6 10/22/2012 1:15           0        326        NW
>>> 
>>>> class(Sandy)
>>> [1] "data.frame"
>>> 
>>>> str(Sandy)
>>> 'data.frame':   1832 obs. of  4 variables:
>>>  $ Deal1         : chr  "10/22/2012 0:00" "10/22/2012 0:15" "10/22/2012
>>> 0:30" "10/22/2012 0:45" ...
>>>  $ Rainfall_cm   : num  0 0 0 0 0 0 0 0 0 0 ...
>>> 
>>>  $ Wind_Direction: num 296 317  323   323  326  326
>>> 
>>>  $ Wind_Direction: chr  "W" "NW" "NW" "NW" ...
>>> 
>>>> require(ggplot2)
>>> Loading required package: ggplot2
>>> 
>>> # this graph does the precipitation vs time graph, but not the wind
>>> 
>>>> ggplot(Sandy, aes(x = Deal1, y = Rainfall_cm, group = 1)) +
>>> geom_line(stat = "identity")
>>> 
>>> 
>>> Ideally I want it to have the precipitation graph vs time, then wind vs
>>> time on the same graph. I would like the wind direction to be arrows
>>> pointing in the designated direction (i.e. North points north).
>>> 
>>> Thank you!
>>> 
>>>       [[alternative HTML version deleted]]
>>> 
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>>> PLEASE do read the posting guide
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>>> and provide commented, minimal, self-contained, reproducible code.
>> 
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>> R-help at r-project.org mailing list -- To UNSUBSCRIBE and more, see
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