Merging clima data and Subnational level Population Weighted Density (PWD)

[Pedro Troncoso]

Dear Statalist,

I am working on my research project that involves relating climate and Subnational level Population Weighted Density (PWD) data for the year 2000. I have obtained the following files

(1) Weather files:
http://climate.geog.udel.edu/~climat...oad.html#P2017
From here I get, precip_2017.tar.gz (284MB) --> precip_2017 --> precip.2000

(2) Subnational level Population Weighted Density (PWD) files:
https://hub.worldpop.org/geodata/summary?id=50576
From here I get, PWD_1km_sub_national_SHP.zip (2.20 MB) --> PWD_1km_sub_national_SHP --> PWD_2000_sub_national_1km.shp

(3) As the PWD files are produced using GADM (version 3.6) level 1 administrative unit boundaries, these files have been obtained from:
https://data.biogeo.ucdavis.edu/data...levels_shp.zip
From here I get, gadm36_levels_shp.zip --> gadm36_levels_shp --> gadm36_0.shp (shapefile of country boundaries), gadm36_1.shp (shapefile using in PWD)

To relate the ID of the points of PWD_2000_sub_national_1km.shp with the spatial data of precip.2000, I have done the following

** The shapefile for the points
* To install: ssc install shp2dta
shp2dta using "PWD_1km_sub_national_SHP/PWD_2000_sub_national_1km.shp", /// 
    data("PWD_2000_points_data.dta") coor("PWD_2000_points_coor.dta") replace

** Import weather data one time period
infile lon lat p1 p2 p3 p4 p5 p6 p7 p8 p9 p10 p11 p12 p2000 /// 
    using "precip_2017/precip.2000", clear

** Reduce to grid coordinates and data
keep lat lon p2000
order lat lon p2000
isid lat lon, sort

** Match grid coordinates to points of countries
* To install: ssc install geoinpoly
geoinpoly lat lon using "PWD_2000_points_coor.dta"

When executing the Code, it tells me "a polygon must start with missing coordinates" How can I make the ID of PWD appear in precip.2000?

I'm hoping someone who has experience working with this kind of data and might have a solution.

Thank you!
Pedro

[Justin Niakamal]

I'm not at all familar with any of this data, but the issue appears to be PWD_2000_sub_national_1km.shp, which is not a polygon file. You might have to map those points to polygon file beforehand. Example --

clear all

// Get files
copy "https://data.biogeo.ucdavis.edu/data/gadm3.6/gadm36_levels_shp.zip" "gadm36_levels_shp.zip"
unzipfile gadm36_levels_shp.zip


copy "https://data.worldpop.org/GIS/Population_Weighted_Density/Unconstrained_Subnational/1km/PWD_1km_sub_national_SHP.zip" "PWD_1km_sub_national_SHP.zip"
unzipfile PWD_1km_sub_national_SHP.zip

      
copy "http://climate.geog.udel.edu/~climate/html_pages/Global2017/precip_2017.tar.gz" "precip_2017.tar.gz"
shell gunzip precip_2017.tar.gz  
shell tar -xf precip_2017.tar


shp2dta using "PWD_1km_sub_national_SHP/PWD_2000_sub_national_1km.shp", ///
        data("PWD_2000_points_data.dta") coor("PWD_2000_points_coor.dta") replace

shp2dta using "gadm36_1", ///
        data("points_data.dta") coor("coor.dta") replace


// This is the "polygon" (coordinates) file
use PWD_2000_points_coor, clear

spmap using "coor.dta" , id(_ID) ocolor(black ..) osize(0.05 ..)  point(xcoord(_X) ycoord(_Y)  data(PWD_2000_points_coor)  fcolor(blue%50 ..) size(vsmall))

exit

[Pedro Troncoso]

Hi @Justin Niakamal

Thank you very much for your Stylized Example. I followed your Code indicated in #2 and I get the same results! However, it doesn't solve the problem I have...

The problem I have is that I need to associate the 3496 _IDs of the "PWD_2000_points_coor.dta" file with the precip.2000 file (from precip_2017) but doing this directly following the Code indicated in #1 returns the specified error.

Using shp2dta I can associate the 3610 _IDs from the "coor.dta" file coming from gadm36_1.shp (used to generate the PWD metrics) with the precip.2000 file, but then I don't know what else to do to leave only the 3496 _ID of the file "PWD_2000_points_coor.dta" to later merge its metrics with " PWD_2000_points_data.dta".

[Justin Niakamal]

Hi Pedro Troncoso, yes it won't solve your problem. The code in #2 is to highlight the issue with the PWD_2000_points_coor.dta file. The .shp file isn't a polygon file, so your code in #1 won't work because

geoinpoly lat lon using "PWD_2000_points_coor.dta"

PWD_2000_points_coor.dta needs to be a polygon file, but as shown in my code it appears to just be the centroid of some polygon (as mentioned before, I'm not at all familiar with this data).

[Pedro Troncoso]

Hi Justin Niakamal, thank you very much for your concern and for answering me. I will keep searching to solve my problem...