Display several polygons at once with matplotlib by getting Google Vision API data in the right format

Question

My goal is to display several polygons at once (this is data I'm getting from Google Vision API).

I have a list of coordinates in this format:

lst_coord = [['(742,335),(840,334),(840,351),(742,352)'], ['(304,1416),(502,1415),(502,1448),(304,1449)']

Knowing that those are strings:

(742,548),(814,549),(814,563),(742,562)
<class 'str'>

import matplotlib.pyplot as plt

def plotpoly(coord,x,y):

    coord.append(coord[0])
    x, y = zip(*coord) 
    plt.plot(x,y)

for coord in lst_coord:
    plotpoly(coord,x,y)

plt.show() 

I'm getting this error:

AttributeError: 'str' object has no attribute 'append'

I've tried quite a few different things. But I can't get it to work...

Bonus: My final goal is to display those polygons on a picture and I'm also struggling with this...

Answer 1

You can use Polygon patches, they will close automatically:

import matplotlib.pyplot as plt
from matplotlib.patches import Polygon
from matplotlib.collections import PatchCollection

lst_coord = [['(742,335),(840,334),(840,351),(742,352)'], ['(304,1416),(502,1415),(502,1448),(304,1449)']]
patches = []
for coord in lst_coord:
    patches.append(Polygon(eval(coord[0])))
    
fig, ax = plt.subplots()
ax.add_collection(PatchCollection(patches, fc='none', ec='red'))
ax.set_xlim(0,1000)
ax.set_ylim(0,1500)
plt.show()