CODEWITHSUNDEEP
pythonpython-3.xtuples
seetlmarkjae
seetlmarkjae

Reputation: 11

how to plot tuples on 2d list (python)

hi im trying to read a text file that gives me coordinates that I need to plot on a 2d list. my text file is simple and contains the plots with x,y for each line already. this is what it looks contains:

3,2

3,3

3,4

4,4

4,5

4,6

so far I've been able to extract the coordinates from the file but I'm stuck on how to get the tuples plotted. here's my code:

fnhandle = open(file_name)  
    lines = fnhandle.readlines()
    lines = [item.rstrip("\n") for item in lines]
    r_c_coordinates = list()
    for item in lines:
            item = item.split(",")
            item = tuple(int(items) for items in item)
            r_c_coordinates.append(item)                
    fnhandle.close()

edit: by "plot" I mean that I have an initialized 2d list that contains 0's. i have to go back to the 2d list at the coordinates of the tuples and change these to 1's

Upvotes: 1

Views: 1074

Answers (2)

cdlane
cdlane

Reputation: 41872

by "plot" I mean that I have an initialized 2d list that contains 0's. i have to go back to the 2d list at the coordinates of the tuples and change these to 1's

An example of plotting points in a grid in memory:

file_name = "points.txt"

my_grid = [[0] * 10 for _ in range(10)]  # 10 by 10 grid of zeros

def print_grid(grid):
    for row in grid:
        print(*row)

print_grid(my_grid)

r_c_coordinates = list()

with open(file_name) as file:
    for line in file:
        coordinate = [int(n) for n in line.rstrip().split(',')]
        r_c_coordinates.append(tuple(coordinate))

for row, column in r_c_coordinates:
    my_grid[column][row] = 1

print('- ' * len(my_grid[0]))
print_grid(my_grid)

I'm assuming zero-based coordinates.

OUTPUT (with annotation)

> python3 test.py
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
- - - - - - - - - - 
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 1 0 0 0 0 0 0  # 3,2
0 0 0 1 0 0 0 0 0 0  # 3,3
0 0 0 1 1 0 0 0 0 0  # 3,4 & 4,4
0 0 0 0 1 0 0 0 0 0  # 4,5
0 0 0 0 1 0 0 0 0 0  # 4,6
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0
>

Upvotes: 0

JimmyCarlos
JimmyCarlos

Reputation: 1952

If by "plot", you mean on a 2D graph, this is probably the simplest way:

import matplotlib.pyplot as plt
x_coords = [coord[0] for coord in r_c_coordinates]
y_coords = [coord[1] for coord in r_c_coordinates]
plt.plot(x_coords, y_coords, "k.", lw=0)

Upvotes: 2

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