Geometric objects in shapely

Preface

Main reference shapely Official documents .
Recently, some vector data needs to be processed in the project , Under the trend of curiosity , Want to know how these vector data are stored , And then I looked up some information , Make a brief summary of the information found so far .

Shapely The geometry involved in is mainly 2D, Although there is one z Coordinates but in actual geometric analysis , Hardly use , Negligible . And the constructed geometric objects will convert the value to float type
There are four types of geometric objects ： spot (Point)、 Line (LineString)、 closed loop (LinearRing)、 Noodles (Polygon)

spot (Point)

There is basically nothing to pay special attention to

#  Construction point 
from shapely.geometry import Point
point = Point(1,1)
#  area , length , Frame 
point.area
point.length
point.bounds

point.corrds #  coordinate 
point.corrds[:] #  Coordinate slice 
Point(point) #  Directly copy other point information to build points 

Line (LineString) and closed loop (LinearRing)

The two should be distinguished , Examples of differences between the two are as follows

from shapely.geometry import LineString
line = LineString([(0,0), (1,1), (2,0), (2,2), (0,2)])
line

from shapely.geometry.polygon import LinearRing
ring = LinearRing([(0,0), (1,1), (2,0), (2,2), (0,2)])
ring

Example 2

ring2 = LinearRing([(0,0), (1,1), (2,0), (2,2), (1,1),(0,2)])
ring2
line2 = LineString([(0,0), (1,1), (2,0), (2,2), (1,1),(0,2)])
line2

But both have length and no area .

ring.area
Out[13]: 0.0

ring.length
Out[14]: 8.82842712474619

line.area
Out[15]: 0.0

line.length
Out[16]: 6.82842712474619

Other attribute references Point

Noodles (Polygon)

Noodles , Also called polygon , The official definition of ：
class Polygon(shell[, holes=None])
Notice the difference between the brackets , The face accepts two parameters ：
One is Orderly (x,y[,z]) Dot tuple , Simply put, there is a LinearRing, This is in gdal It's similar inside , That is to say, the structural surface is formed after the closing operation with a line loop .
The other is Optional unordered Of Circular sequence , It is used to represent the internal boundary or “ hole ”.

LinearRing And Polygon What's the difference ？
LinearRing