Chapter 2 — Practice Spatial Vector Data with GeoPandas

GeoPandas library is to make working with spatial data in python easier that combining the capabilities of pandas and shapely, providing spatial operations in pandas and a high-level interface to multiple geometries to shapely.

2.1 Data Structures

GeoPandas implements two main data structures, a GeoSeries and a GeoDataFrame. These are subclasses of pandas Series and DataFrame, respectively.

a) GeoSeries

A GeoSeries is a vector where each entry in the vector is a set of shapes corresponding to one observation.

Geopandas has three basic classes of geometric objects (which are actually shapely objects): Points / Multi-Points, Lines / Multi-Lines, Polygons / Multi-Polygons.

Examples: Points, Lines and Polygons

import geopandas
from shapely.geometry import Point
s = geopandas.GeoSeries([Point(1, 1), Point(2, 2), Point(3, 3)])
s

0    POINT (1.00000 1.00000)
1    POINT (2.00000 2.00000)
2    POINT (3.00000 3.00000)
dtype: geometry

from shapely.geometry import LineString
l= geopandas.GeoSeries([LineString([Point(-77.036873,38.907192), Point(-76.612190,39.290386,), Point(-77.408456,39.412006)])])
l

0    LINESTRING (-77.03687 38.90719, -76.61219 39.2...
dtype: geometry

from shapely.geometry import Polygon
p= geopandas.GeoSeries([Polygon([(-77.036873,38.907192), (-76.612190,39.290386,), (-77.408456,39.412006)])])
p

0    POLYGON ((-77.03687 38.90719, -76.61219 39.290...
dtype: geometry

b) GeoDataFrame

A GeoDataFrame is a tabular data structure that contains a GeoSeries.

A GeoDataFrame may also contain other columns with geometrical (shapely) objects, but only one column can be the active geometry at a time. To change which column is the active geometry column, use the GeoDataFrame.set_geometry() method.

Example:

world = geopandas.read_file(geopandas.datasets.get_path('naturalearth_lowres'))
world.head()

 pop_est      continent                      name iso_a3  gdp_md_est  \
0     889953.0        Oceania                      Fiji    FJI        5496   
1   58005463.0         Africa                  Tanzania    TZA       63177   
2     603253.0…