Steps to create spatial plots

[lily li]

Hi users,

I have no clear clue about plotting spatial data. For example, I just have a table with attribute values of each grid cell, such as elevation. Then I have coordinates of the upper left corner in UTM, the number of rows and columns, and grid cell size. How to create spatial plot of elevations for the grid cells, in color ramp? Should I create a spatial grid layer with all the polygons first? Thanks.

[Roman Luštrik]

You will need to coerce your data into a "spatial" kind, as implemented in `sp` or as of late, `sf` packages. You might want to give the vignettes a whirl before you proceed.

Roughly, you will have to coerce the data to Spatial* (you could go for a point, raster or grid type, I think) and also specify the projection. Once you have that, plotting should be handled by packages.

Here are a few quick links that might come handy:

https://cran.r-project.org/web/views/Spatial.html

http://www.datacarpentry.org/R-spatial-raster-vector-lesson/10-vector-csv-to-shapefile-in-r/

Cheers,

Roman

On Mon, Jan 15, 2018 at 11:22 PM, lily li <choc...@gmail.com> wrote:

Hi users,

I have no clear clue about plotting spatial data. For example, I just have a table with attribute values of each grid cell, such as elevation. Then I have coordinates of the upper left corner in UTM, the number of rows and columns, and grid cell size. How to create spatial plot of elevations for the grid cells, in color ramp? Should I create a spatial grid layer with all the polygons first? Thanks.

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[Adriano Fantini]

the latest ggplot from github (to be installed with `devtools:install_github()`) has support for SF objects too, it's a treat!

However, sf is not exactly designed for raster data. Of course you can make each of your cells be a square polygon, but it's not the most efficient way for big datasets. For this the `raster` (excellent and rock stable) and `stars` (even more excellent, but in heavy development) can be used.

Adriano Fantini