From a4bba0b9594dc02ea842f2c653c530e6913a0907 Mon Sep 17 00:00:00 2001
From: Philipp Oppermann <dev@phil-opp.com>
Date: Mon, 4 Sep 2023 11:28:47 +0200
Subject: [PATCH] Improve Python ROS2 example

- reduce rate of Twist messages (every 500ms instead of triggered by received Pose)
- print received Pose messages on single line to prevent splitting in logs
---
 examples/python-ros2-dataflow/control_node.py | 26 +++++++++----------
 examples/python-ros2-dataflow/dataflow.yml    |  2 +-
 .../python-ros2-dataflow/random_turtle.py     |  6 +----
 3 files changed, 15 insertions(+), 19 deletions(-)

diff --git a/examples/python-ros2-dataflow/control_node.py b/examples/python-ros2-dataflow/control_node.py
index 6355e065..15ec4bdd 100755
--- a/examples/python-ros2-dataflow/control_node.py
+++ b/examples/python-ros2-dataflow/control_node.py
@@ -12,16 +12,16 @@ for i in range(500):
     if event is None:
         break
     if event["type"] == "INPUT":
-        print(
-            f"""Node received:
-    id: {event["id"]},
-    value: {event["value"]},
-    metadata: {event["metadata"]}"""
-        )
-        node.send_output(
-            "direction",
-            pa.array(
-                [random.random() + 1, 0, 0, 0, 0, (random.random() - 0.5) * 5],
-                type=pa.float64(),
-            ),
-        )
+        match event["id"]:
+            case "turtle_pose":
+                print(
+                    f"""Pose: {event["value"]}""".replace("\r", "").replace("\n", " ")
+                )
+            case "tick":
+                node.send_output(
+                    "direction",
+                    pa.array(
+                        [random.random() + 1, 0, 0, 0, 0, (random.random() - 0.5) * 5],
+                        type=pa.float64(),
+                    ),
+                )
diff --git a/examples/python-ros2-dataflow/dataflow.yml b/examples/python-ros2-dataflow/dataflow.yml
index e1f8d936..809c8d95 100644
--- a/examples/python-ros2-dataflow/dataflow.yml
+++ b/examples/python-ros2-dataflow/dataflow.yml
@@ -4,7 +4,6 @@ nodes:
       source: ./random_turtle.py
       inputs:
         direction: control/direction
-        tick: dora/timer/millis/50
       outputs:
         - turtle_pose
 
@@ -13,5 +12,6 @@ nodes:
       source: ./control_node.py
       inputs:
         turtle_pose: turtle/turtle_pose
+        tick: dora/timer/millis/500
       outputs:
         - direction
diff --git a/examples/python-ros2-dataflow/random_turtle.py b/examples/python-ros2-dataflow/random_turtle.py
index 4fef3571..caf96ec1 100755
--- a/examples/python-ros2-dataflow/random_turtle.py
+++ b/examples/python-ros2-dataflow/random_turtle.py
@@ -53,15 +53,11 @@ for i in range(500):
 
                             direction_arrow = pa.array([pa.scalar(direction)])
                             twist_writer.publish(direction_arrow)
-                        case "tick":
-                            pass
 
         case "external":
             pose = event.inner()[0].as_py()
 
-            assert (
-                pose["x"] != 5.544445
-            ), "turtle should not be at initial x axis"
+            assert pose["x"] != 5.544445, "turtle should not be at initial x axis"
             dora_node.send_output(
                 "turtle_pose",
                 pa.array(