Displaying points fetched from table as web map? [closed]

Question

I have at hand a common GIS task:

The data: I posses 16,000 Excel rows. Each has latitude and longitude and some other attributes. I need to build a program that allows the user to type in a location and a radius and then the program will look up the data and fetch only those points that fall within the given radius. The output should be a map with the fetched points displayed, but also a table listing the points that fall within the radius.

I am aiming for a web mapping solution.

Also, what programming language do you think would be suited for this?

Any particular web map API?

I am good at Python, but not so good at Javascript.

Answer 1

I'd recommend following technology stack: a PostGIS database in combination with a python backend (I recommend flask - http://flask.pocoo.org/) serving JSON, which then gets displayed in the frontend on a map powered by leaflet (http://leafletjs.com/) and some sprinkles of javascript to render the attribute table; a framework like backbone or angularjs would be overkill.

Here is a sample for the python backend (be aware that this is just a quick and messy example which should never be run in production!). It queries against the geonames dataset and returns id and name as attribute to display in a table as well as a geojson to display in a map. The query-url would be:

host/search?lat=48&lon=12&rad=1

with the radius rad in degrees.

from flask import Flask, jsonify, url_for, request
import psycopg2
import json

conn = psycopg2.connect(database='***', user='***')
  curs = conn.cursor()

app = Flask(__name__)

@app.route("/search")
def search():
  # GET data from request
  data = (request.args.get('lat', ''), request.args.get('lon', ''), request.args.get('rad', ''))

  # Query PostGIS
  curs.execute("""\
    SELECT geonameid, name, ST_Distance(geom, point) as distance, ST_AsGeoJSON(geom)
    FROM geotest, (SELECT ST_MakePoint(%s, %s) AS point) AS f
    WHERE ST_DWithin(geom, point, %s)
    ORDER BY ST_Distance(geom, point) ASC;""", data)
  res = []

  # build response
  for row in curs.fetchall():
    rec = {"id": row[0], "name": row[1], "distance": row[2], "geojson": json.loads(row[3])}
    res.append(rec)

  # serve response
  resp_data = json.dumps(res)
  return Response(resp_data, status=200, mimetype='application/json')

if __name__ == "__main__":
  app.debug = True
  app.run()