[R] how to plot gridded data

Roy Mendelssohn - NOAA Federal roy@mende|@@ohn @end|ng |rom no@@@gov
Fri Sep 14 04:15:12 CEST 2018

Hi Lily:

I haven't used it to any extent to give you specifics,  but I strongly suggest you look at the package sf,  it is designed to do these sorts of things.  sf can read in the shapefile,  and it has features to covert the dataframe you describe to one of its objects,  and to combine objects.  There are even plotting functions I believe,  or if not there is a ggplot2::geom_sf()



> On Sep 13, 2018, at 7:02 PM, lily li <chocold12 using gmail.com> wrote:
> Hi Petr,
> I have merged the data using cbind. The dataset is like this:
> DF
> lat1_lon1  lat1_lon2  lat1_lon3  ...  lat2_lon1
>  1.20           1.30          2.11      ...     1.28
>  1.50           1.81          3.12      ...     2.34
>  2.41           2.22          1.56      ...     2.50
>  3.11           4.21          2.12      ...     3.21
> The other file is a shapfile, which I can open using readOGR. Then it shows
> a polygon according to geographical latitude and longitude in degrees. How
> to overlay the values in DF onto the polygon? note that DF has the
> coordinates for a rectangular box that includes the shapefile, but is
> larger. I don't know how to do this. Thanks for your help.
> On Wed, Sep 12, 2018 at 3:22 PM, PIKAL Petr <petr.pikal using precheza.cz> wrote:
>> Hi
>> 1. Read files/lines into R ?read.table, ?read.lines
>> 2. Merge files according to your specification ?merge, ?rbind
>> 3. Plot values by suitable command(s) ?plot, ?ggplot
>> 4. If you want more specific answer, please post more specific question,
>> preferably with concise and clear example.
>> 5. Avoid posting in HTML
>> Cheers
>> Petr
>>> -----Original Message-----
>>> From: R-help <r-help-bounces using r-project.org> On Behalf Of lily li
>>> Sent: Wednesday, September 12, 2018 8:55 AM
>>> To: R mailing list <r-help using r-project.org>
>>> Subject: [R] how to plot gridded data
>>> Hi R users,
>>> I have a question about plotting gridded data. I have the files
>> separately, but do
>>> not know how to combine them. For example, each txt file has daily
>>> precipitation data at a specific grid cell, named pr_lat_lon.txt. How to
>> plot all
>>> txt files for one surface (which is rectangular in this case), or how to
>> combine
>>> the txt files together? Thanks.
>>> [[alternative HTML version deleted]]
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> 	[[alternative HTML version deleted]]
> ______________________________________________
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"The contents of this message do not reflect any position of the U.S. Government or NOAA."
Roy Mendelssohn
Supervisory Operations Research Analyst
Environmental Research Division
Southwest Fisheries Science Center
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