CODEWITHSUNDEEP
pythongeospatialgeoshapely
four-eyes
four-eyes

Reputation: 12508

Creating Points from Coordinate-Tuple-List with shapely

I have a coordinates list looking like so 

myCoordinates
> [(2, -6), (21, 19)]

I want to convert them into shapely geometry objects so that I can do some calculations with them:

from shapely.geometry import Point
for i in myCoordinates:
    c = [Point(i[0], i[1])]

print c
> [<shapely.geometry.point.Point object at 0x1044033d0>]

However, that only gives me one (!) geometry object.

But when I do this 

circles = [Point(random.random(), random.random()).buffer(random.random() * 0.1) for i in range(3)]

I get three geometry objects.

print circles
> [<shapely.geometry.polygon.Polygon object at 0x1043f6890>, <shapely.geometry.polygon.Polygon object at 0x10442f8d0>, <shapely.geometry.polygon.Polygon object at 0x10442f910>]

What am I doing wrong? Why is it only converting one Point into a geometry object and not the two in my list?

Upvotes: 3

Views: 14315

Answers (2)

Trev Davies
Trev Davies

Reputation: 391

You are overwriting your variable in each iteration of the loop. You need to make c a list and then append to it:

from shapely.geometry import Point
c = []
for i in myCoordinates:
    c.append([Point(i[0], i[1])])

print c

Or you can do it all in one line with a list comprehension:

c = [Point(coord[0], coord[1]) for coord in myCoordinates]

Upvotes: 6

AKS
AKS

Reputation: 19871

Following would give you three points:

c = [Point(i[0], i[1]) for i in myCoords]

It follows the same list comprehension as the circles:

circles = [Point(random.random(), random.random()).buffer(random.random() * 0.1) for i in range(3)]

What you were doing earlier is assigning the point to a variable c so at the end of the for loop, there is just one point in a list:

for i in myCoordinates:
    c = [Point(i[0], i[1])] # here c is overwritten in each iteration

Upvotes: 2

Related Questions