Epidemiology & Technology

Blog Archive

Understanding GeoJSON data

GeoJSON files are a standard way of storing GIS data These contain not only the coordinates but also the attribute data. These files have a key: value based hierarchial data structure You may think of these keys as variable names and values as the dara. In computer science terminology, these are
January 25, 2021

Removing and Updating GEOJSON Layers in Leaflet Maps, Using LayerGroups in Leaflet

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Use Case: Let us map it Directrory structure The html has a state selection dropdown The state geoJSONs are saved as 1.geojson, 2.geojson etc in the geo directory. We attach an event listner to the Dropdown Select control and show state layers absed on selection So what are these layergroups?
January 22, 2021

Making a HTML Table from GeoJSON data

GeoJSON objects have a "Type" : "FeaturesCollection" property and a "Features" property whose value is an array of objects. Each child object of this has "type" = "feature", "geometry" = containes the GIS Coordinate data"properties" = contains the attribute data - Name, address, contact, facilities, serivices, whjatever catches your fancy
January 22, 2021

Loading GeoJSON data with Leaflet Maps

Loading GeoJSON data files can be network intensive if the GIS data has good resolution or if the number of features being added is high. In such scenario, it is better to load the GeoJSON data file separately and not include it as part of the main HTML or main
January 22, 2021

India GIS Map with Leaflet

We will use Leaflet.js to make a map of India. This uses a GeoJSON dataset for India which has been simplified using www.MapShaper.org. The states for Telangana and Andhra Pradesh appear separate. J&K is as per India official position. There are nice pop-overs for state names. Lets Dive in HTML
September 30, 2019