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def build_linestring_gdf(gdf, sortby, groupby):
    crs = gdf.crs
    gdf = gdf.sort_values(sortby).groupby(groupby).geometry.apply(lambda x: LineString(x.tolist()))
    return GeoDataFrame({groupby: gdf.index}, crs=crs, geometry=gdf.values)

def build_point_gdf(df, xcol, ycol, crs={'init': 'epsg:4326'}):
    geometry = [Point(x, y) for x, y in zip(df[xcol], df[ycol])]
    df = df.drop([xcol, ycol], axis=1)
    gdf = GeoDataFrame(df, crs=crs, geometry=geometry)
    return gdf

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from random import random

def epproximate(count, debug=False):
    cumsum = 0.

    for i in range(int(count)):
        x = 0
        while x <= 1:
            x += random()
            cumsum += 1

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Guide to converting a postgres table to shapefile

Run brew install gdal --with-postgresql to install the ogr2ogr utility.

Then run the following command to create a shapefile from the table:

ogr2ogr -f "ESRI Shapefile" myshape.shp PG:"<db url>" "my_db_table"

Finally, you’ll need to zip the myshape.* files together.

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border: no
license: gpl-3.0

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require "pg"

# Credit:
# https://git.io/vDQet
# https://git.io/vDQeZ

# Total Cash test
#
# Another famous test of snapshot isolation anomaly.
#

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# app/controllers/users_controller.rb
class UsersController < ApplicationController
  def index
    # users = User.includes(:orgs).order(:id).page(params[:page] || 1)
    users = User.order(:id).page(params[:page] || 1)
    render json: users, include: :orgs
  end
end