grid50: Grids partitioning the surface of Earth into n equal areas.

In R2G2: Converting R CRAN outputs into Google Earth.

Description

Sets of precomputed grids that partition the Earth's surface into equal areas.

Usage

data(grid50)

Details

The available grids provide 50, 500, 5000, 10'000 and 20'000 equal area cells. The coordinates are given in radians. They can be converted into lat / lon decimal degrees using the code provided as an example.

Author(s)

Nils Arrigo, [e-mail] 2012 EEB, the University of Arizona, Tucson

References

http://eqsp.sourceforge.net/ https://etna.mcs.kent.edu/vol.25.2006/pp309-327.dir/pp309-327.html

Leopardi, P. "A partition of the unit sphere into regions of equal area and small diameter" (2006). Electronic Transactions on Numerical Analysis 25:309-327.

Examples

#Converting grid50 (radians) to usual decimal degrees
data(grid50)
Rad2DD = function(lon, lat){
  lonDD = 360 * round((lon / (2 * pi)), 5) - 180 + 0.01
  latDD = 180 * round(lat / pi, 5) - 90 + 0.01
  cbind(lonDD, latDD)
  }
grid50DD = Rad2DD(grid50[,2], grid50[, 3])
grid50DD

#Converting decimal degrees to grid50 format (radians and properly centered)
DD2Rad = function(lon, lat){
  lonrad = (lon + 180) * pi/180
  latrad = (lat + 90) * pi/180
  cbind(lonrad, latrad)
  }
grid50Rad = DD2Rad(grid50DD[ ,1], grid50DD[ ,2])  
grid50Rad = data.frame("1", grid50Rad) #this step is only cosmetic and necessary for compatibily issues.
grid50Rad

Example output

          lonDD    latDD
 [1,] -179.9900 -89.9900
 [2,] -154.2752 -58.2812
 [3,] -102.8456 -58.2812
 [4,]  -51.4196 -58.2812
 [5,]    0.0100 -58.2812
 [6,]   51.4396 -58.2812
 [7,]  102.8692 -58.2812
 [8,]  154.2952 -58.2812
 [9,] -170.6408 -28.3562
[10,] -137.9132 -28.3562
[11,] -105.1856 -28.3562
[12,]  -72.4580 -28.3562
[13,]  -39.7304 -28.3562
[14,]   -7.0028 -28.3562
[15,]   25.7248 -28.3562
[16,]   58.4524 -28.3562
[17,]   91.1800 -28.3562
[18,]  123.9076 -28.3562
[19,]  156.6352 -28.3562
[20,] -172.0016   0.0100
[21,] -142.0028   0.0100
[22,] -112.0040   0.0100
[23,]  -82.0016   0.0100
[24,]  -52.0028   0.0100
[25,]  -22.0040   0.0100
[26,]    7.9984   0.0100
[27,]   37.9972   0.0100
[28,]   67.9960   0.0100
[29,]   97.9984   0.0100
[30,]  127.9972   0.0100
[31,]  157.9996   0.0100
[32,] -167.9120  28.3780
[33,] -135.1844  28.3780
[34,] -102.4568  28.3780
[35,]  -69.7292  28.3780
[36,]  -37.0016  28.3780
[37,]   -4.2740  28.3780
[38,]   28.4536  28.3780
[39,]   61.1776  28.3780
[40,]   93.9052  28.3780
[41,]  126.6328  28.3780
[42,]  159.3604  28.3780
[43,] -146.8736  58.3030
[44,]  -95.4440  58.3030
[45,]  -44.0144  58.3030
[46,]    7.4116  58.3030
[47,]   58.8412  58.3030
[48,]  110.2708  58.3030
[49,]  161.7004  58.3030
[50,] -179.9900  90.0100
   X.1.       lonrad       latrad
1     1 0.0001745329 0.0001745329
2     1 0.4489824594 0.5535974948
3     1 1.3465983124 0.5535974948
4     1 2.2441513335 0.5535974948
5     1 3.1417671865 0.5535974948
6     1 4.0393830395 0.5535974948
7     1 4.9369988925 0.5535974948
8     1 5.8345519136 0.5535974948
9     1 0.1633488554 1.0758872734
10    1 0.7345532316 1.0758872734
11    1 1.3057576079 1.0758872734
12    1 1.8769619842 1.0758872734
13    1 2.4481663605 1.0758872734
14    1 3.0193707367 1.0758872734
15    1 3.5905751130 1.0758872734
16    1 4.1617794893 1.0758872734
17    1 4.7329838656 1.0758872734
18    1 5.3041882418 1.0758872734
19    1 5.8753926181 1.0758872734
20    1 0.1395984149 1.5709708597
21    1 0.6631762465 1.5709708597
22    1 1.1867540782 1.5709708597
23    1 1.7103947417 1.5709708597
24    1 2.2339725733 1.5709708597
25    1 2.7575504050 1.5709708597
26    1 3.2811910685 1.5709708597
27    1 3.8047689001 1.5709708597
28    1 4.3283467318 1.5709708597
29    1 4.8519873953 1.5709708597
30    1 5.3755652269 1.5709708597
31    1 5.8992058904 1.5709708597
32    1 0.2109754000 2.0660858619
33    1 0.7821797763 2.0660858619
34    1 1.3533841525 2.0660858619
35    1 1.9245885288 2.0660858619
36    1 2.4957929051 2.0660858619
37    1 3.0669972814 2.0660858619
38    1 3.6382016576 2.0660858619
39    1 4.2093432021 2.0660858619
40    1 4.7805475783 2.0660858619
41    1 5.3517519546 2.0660858619
42    1 5.9229563309 2.0660858619
43    1 0.5781647493 2.5883756406
44    1 1.4757806023 2.5883756406
45    1 2.3733964553 2.5883756406
46    1 3.2709494764 2.5883756406
47    1 4.1685653294 2.5883756406
48    1 5.0661811824 2.5883756406
49    1 5.9637970354 2.5883756406
50    1 0.0001745329 3.1417671865

R2G2 documentation built on May 29, 2017, 1:41 p.m.