lat-long-points-generator

General

Simple script that generates regularly points (latitude, longitude) that covers the earth according to a given step in degree. The resulting points are writen in a csv file.

In details

The idea

The idea is to "split the earth" in small squares, in order to get discrete data which is faster to process until a certain limit. The points are not centered inside the squares since the algorithm starts from (-90, -180) included and goes until (90, 180) excluded. In that case, the points are placed in the left-bottom corner.

To illustrate

Here is an illustration using a step equals to 60 degrees:

             ___________________ (30, 120)
             |. |. |. |. |. |. |
             ⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻
             |. |. |. |. |. |. |
             ⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻
             |. |. |. |. |. |. |
(-90, -180)  ⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻⎻

The step

The step is the granularity parameter in degrees used to split the earth. Lower is the step better the accuracy is, but more points you get:

• 0.1 is about 11.1km
• 0.01 is about 1.11km
• 0.001 is about 110m
• 0.0001 is about 11m

Of the course these figures are approximated since it depends on where the points are taken on the earth. if your goal is to have a regular step in meters then this generator is not adapted.

for a step equals to 0.05deg:

• 5km
• 25'920'000 points
• csv size 566.3MB

How to use

$ chmod +x lat-long-points-generator.py

# executes with default step 0.05
$ ./lat-long-points-generator.py

# executes for a given step
$ ./lat-long-points-generator.py 0.8

# quick check on the result
tail array_index.csv   

89.95,179.5,25919990
89.95,179.55,25919991
89.95,179.6,25919992
89.95,179.65,25919993
89.95,179.7,25919994
89.95,179.75,25919995
89.95,179.8,25919996
89.95,179.85,25919997
89.95,179.9,25919998
89.95,179.95,25919999

latitude, longitude, index