[R] merging df with world map

[boB Rudis]

you also don't need to do a merger if you use a base `geom_map()`
layer with the polygons and another using the fill (or points, lines,
etc).

On Fri, Jun 17, 2016 at 5:08 PM, MacQueen, Don <macqueen1 at llnl.gov> wrote:
> And you can check what David and Jeff suggested like this:
>
> intersect( df$COUNTRY, world_map$region )
>
> If they have any values in common, that command will show them. (Note that
> I said values in common, not countries in common.)
>
> WARNING:
> It appears that you have each country appearing more than once in both of
> the data frames. Even if the country names were spelled the same (which
> they are not in the first few rows), I would not care to predict the
> outcome of a many-to-many merge. It probably won't make sense for showing
> the data on a map.
>
> -Don
>
> --
> Don MacQueen
>
> Lawrence Livermore National Laboratory
> 7000 East Ave., L-627
> Livermore, CA 94550
> 925-423-1062
>
>
>
>
>
> On 6/17/16, 1:06 PM, "R-help on behalf of ch.elahe via R-help"
> <r-help-bounces at r-project.org on behalf of r-help at r-project.org> wrote:
>
>>Hi all,
>>I want to use world map in ggplot2 and show my data on world map. my df
>>is:
>>
>>
>>    $ COUNTRY           : chr  "DE" "DE" "FR" "FR" ..
>>
>>    $ ContrastColor     : int  9 9 9 9 13 9 9 9 9 ..
>>
>>    $ quant             : Factor w/ 4 levels "FAST","SLOW",..I need to
>>merge my df with world_map data which is like this:
>>
>>
>>    world_map=map_data("world")
>>    data.frame':   99338 obs. of  6 variables:
>>    $ long     : num  -69.9 -69.9 -69.9 -70 -70.1 ...
>>    $ lat      : num  12.5 12.4 12.4 12.5 12.5 ...
>>    $ group    : num  1 1 1 1 1 1 1 1 1 1 ...
>>    $ order    : int  1 2 3 4 5 6 7 8 9 10 ...
>>    $ region   : chr  "Aruba" "Aruba" "Aruba" "Aruba" ...
>>    $ subregion: chr  NA NA NA NA ...
>>but by merging my df with world map data I get a data frame with zero
>>observation in it,I use this command for merging:
>>
>>
>>    world_map=merge(world_map,df,by.x="region",by.y="COUNTRY")
>>    str(world_map)
>>
>>    'data.frame':   0 obs. of  133 variables:
>>    $ region            : chr
>>    $ long              : num
>>    $ lat               : num
>>    $ group             : num
>>    $ order             : int
>>    $ subregion         : chr
>>does anyone know what is the problem of this merging that I am currently
>>using?
>>thanks for any help!
>>Elahe
>>
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>
> ______________________________________________
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> and provide commented, minimal, self-contained, reproducible code.