Open3d(Python), How to remove points from .ply

I get pointcloud from my Intel RealSense depth camera. And I want to remove extra points that are far away, how do I put a condition in the code?

Code for getting pointcloud:

import numpy as np
from open3d import *


def main():
    cloud = read_point_cloud("1.ply") # Read the point cloud
    draw_geometries([cloud]) # Visualize the point cloud


if __name__ == "__main__":
    main()

Code for viewing pointcloud:

import pyrealsense2 as rs


pipe = rs.pipeline()
config = rs.config()
config.enable_stream(rs.stream.depth)
pipe.start(config)
colorizer = rs.colorizer()

try:

    frames = pipe.wait_for_frames()
    colorized = colorizer.process(frames)

    ply = rs.save_to_ply("1.ply")
    ply.set_option(rs.save_to_ply.option_ply_binary, False)
    ply.set_option(rs.save_to_ply.option_ply_normals, True)
    ply.process(colorized)

    print("Done")

finally:
    pipe.stop()

That what i want delete:

Answer

The question does not say what points exactly are to be removed. Assuming you can provide a sphere of known radius and center location, the following code will remove any points outside that sphere:

import numpy as np
import open3d

# Read point cloud from PLY
pcd1 = open3d.io.read_point_cloud("1.ply")
points = np.asarray(pcd1.points)

# Sphere center and radius
center = np.array([1.586, -8.436, -0.242])
radius = 0.5

# Calculate distances to center, set new points
distances = np.linalg.norm(points - center, axis=1)
pcd1.points = open3d.utility.Vector3dVector(points[distances <= radius])

# Write point cloud out
open3d.io.write_point_cloud("out.ply", pcd1)