Renaming points in python

Question

I have a collection of new points i,j,k,l with their coordinates (1953.2343076828638, 730.0513627132909), (1069.4232335022705, 5882.057343563125),(2212.5767664977293, 3335.942656436875),(4386.765692317136, 1318.948637286709).

I'm trying to give these points some names as s1,s2,s3,s4.

Also, create two separate lists one with just the point name [s1,s2,s3,s4] and the other one with point name and its coordinate as [s1:(1953.2343076828638, 730.0513627132909),(1069.4232335022705, 5882.057343563125)...]

I have the following code for creating random points.

n = 10
#print(n)

#for k in n:
V = []
V=range(n)
#print("vertices",V)

# Create n random points

random.seed()

pos = {i:(random.randint(0,4000),random.randint(0,5000)) for i in V}
#print("pos =", pos)

points = []
positions = []
for i in pos:
    points.append(pos[i])
    positions.append(i)
    positions.append(pos[i])

Suppose I am forming a new list L with two existing points 4 and 7.Then, L = [4,7]

When I type L[0] in the console it gives me, 4 and pos[L[0]] gives me its coordinates.

But considering my new list K= [i,j,k,l], when I type K[0] in the console it gives me the coordinate, but not its name.

I need to add these points in K to the same list as pos defined above with their coordinates, but with different names. Can someone please help me with this?

For the second part, might want to use dictionaries to keep a key and value together. — El-Chief
– El-Chief, Commented May 27, 2018 at 20:55

jpp · Accepted Answer · 2018-05-27 21:13:22Z

1

To access name and coordinates by index, use a list of tuples. Note that you need to name these explicitly. You should preferably avoid this step by using a list of tuples to store your name-coordinate pairs from the beginning.

To access by name, use a dictionary.

i, j, k, l = (1953.2343076828638, 730.0513627132909),\
             (1069.4232335022705, 5882.057343563125),\
             (2212.5767664977293, 3335.942656436875),\
             (4386.765692317136, 1318.948637286709)

K = [(name, var) for name, var in zip('ijkl', (i, j, k, l))]

## ACCESS BY INDEX
name_coord = K[0]  # ('i', (1953.2343076828638, 730.0513627132909))
name = K[0][0]  # 'i'
coord = K[0][1]  # (1953.2343076828638, 730.0513627132909)

## ACCESS BY NAME
d = dict(K)
coord = d['i']  # (1953.2343076828638, 730.0513627132909)

answered May 27, 2018 at 21:13

jpp

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Nf4r · Accepted Answer · 2018-05-27 21:55:18Z

1

Based on @jpp answer I would go for thing named namedtuple. Dictionaries usually tend to take more space than tuples.

from collections import namedtuple
coord = namedtuple('Coordinate', 'name coord')
i, j, k, l = (1953.2343076828638, 730.0513627132909),\
         (1069.4232335022705, 5882.057343563125),\
         (2212.5767664977293, 3335.942656436875),\
         (4386.765692317136, 1318.948637286709)

 K = [coord(name, var) for name, var in zip('ijkl', (i, j, k, l))]

It allows you to do then:

 c = K[0]
 print(c.name)
 print(c.coord)

answered May 27, 2018 at 21:55

Nf4r

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