How to pass launch args dynamically during launch-time

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I have a launch file that launch 2 ROS2 nodes for each vehicle(uav) I have. I would like to specify the number of vehicles I have while running the launch file so that the correct number of nodes is initialized.

My launch file looks like this:

import os
from time import sleep

from launch import LaunchDescription
from launch_ros.actions import Node
from launch.substitutions import LaunchConfiguration
from launch.actions import DeclareLaunchArgument
from ament_index_python.packages import get_package_share_directory


launch_path = os.path.realpath(__file__).replace("demo.launch.py", "")
ros2_ws = os.path.realpath(os.path.relpath(os.path.join(launch_path,"../../../../..")))

avoidance_path = os.path.join(ros2_ws,"src","avoidance")
avoidance_config_path = os.path.join(avoidance_path,"config")

number_of_uavs = int(input("how many uavs do you want to simulate? "))

def generate_launch_description():

    ld = LaunchDescription()

    for i in range(1, number_of_uavs+1):
        namespace="uav_{:s}".format(str(i))

        config = os.path.join(
        avoidance_config_path,
        namespace,
        "params.yaml"
        )

        avoidance_node = Node(
            package="avoidance",
            namespace=namespace,
            executable="avoidance_client_1",
            output="screen",
            parameters=[config]

        )

        trajectory_controller_node = Node(
            package="offboard_exp",
            namespace=namespace,
            executable="trajectory_controller",
            name="trajectory_controller_{:s}".format(namespace)
        )

        ld.add_action(trajectory_controller_node)
        ld.add_action(avoidance_node)

    return ld

Currently, I use number_of_uavs = int(input("how many uavs do you want to simulate? ")) To get the number of vehicles and then change the namespace of the node in each iteration.

Is there a better way to pass this parameter instead of prompting the user to enter it?