Added Line Iterator

nav2_simple_commander/nav2_simple_commander/line_iterator.py

@@ -0,0 +1,177 @@
+#! /usr/bin/env python3
+# Copyright 2021 Samsung Research America
+# Copyright 2022 Afif Swaidan
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+This is a Python3 API for a line iterator.
+
+It provides the ability to iterate
+through the points of a line.
+"""
+
+from cmath import sqrt
+
+
+class LineIterator():
+    """
+    LineIterator.
+
+    LineIterator Python3 API for iterating along the points of a given line
+    """
+
+    def __init__(self, x0, y0, x1, y1, step_size=1.0):
+        """
+        Initialize the LineIterator.
+
+        Args
+        ----
+            x0 (float): Abscissa of the initial point
+            y0 (float): Ordinate of the initial point
+            x1 (float): Abscissa of the final point
+            y1 (float): Ordinate of the final point
+            step_size (float): Optional, Increments' resolution, defaults to 1
+
+        Raises
+        ------
+            TypeError: When one (or more) of the inputs is not a number
+            ValueError: When step_size is not a positive number
+
+        """
+        if type(x0) not in [int, float]:
+            raise TypeError("x0 must be a number (int or float)")
+
+        if type(y0) not in [int, float]:
+            raise TypeError("y0 must be a number (int or float)")
+
+        if type(x1) not in [int, float]:
+            raise TypeError("x1 must be a number (int or float)")
+
+        if type(y1) not in [int, float]:
+            raise TypeError("y1 must be a number (int or float)")
+
+        if type(step_size) not in [int, float]:
+            raise TypeError("step_size must be a number (int or float)")
+
+        if step_size <= 0:
+            raise ValueError("step_size must be a positive number")
+
+        self.x0_ = x0
+        self.y0_ = y0
+        self.x1_ = x1
+        self.y1_ = y1
+        self.x_ = x0
+        self.y_ = y0
+        self.step_size_ = step_size
+
+        if x1 != x0 and y1 != y0:
+            self.valid_ = True
+            self.m_ = (y1-y0)/(x1-x0)
+            self.b_ = y1 - (self.m_*x1)
+        elif x1 == x0 and y1 != y0:
+            self.valid_ = True
+        elif y1 == y1 and x1 != x0:
+            self.valid_ = True
+            self.m_ = (y1-y0)/(x1-x0)
+            self.b_ = y1 - (self.m_*x1)
+        else:
+            self.valid_ = False
+            raise ValueError(
+                "Line has zero length (All 4 points have same coordinates)")
+
+    def isValid(self):
+        """Check if line is valid."""
+        return self.valid_
+
+    def advance(self):
+        """Advance to the next point in the line."""
+        if self.x1_ > self.x0_:
+            if self.x_ < self.x1_:
+                self.x_ = round(self.clamp(
+                    self.x_ + self.step_size_, self.x0_, self.x1_), 5)
+                self.y_ = round(self.m_ * self.x_ + self.b_, 5)
+            else:
+                self.valid_ = False
+        elif self.x1_ < self.x0_:
+            if self.x_ > self.x1_:
+                self.x_ = round(self.clamp(
+                    self.x_ - self.step_size_, self.x1_, self.x0_), 5)
+                self.y_ = round(self.m_ * self.x_ + self.b_, 5)
+            else:
+                self.valid_ = False
+        else:
+            if self.y1_ > self.y0_:
+                if self.y_ < self.y1_:
+                    self.y_ = round(self.clamp(
+                        self.y_ + self.step_size_, self.y0_, self.y1_), 5)
+                else:
+                    self.valid_ = False
+            elif self.y1_ < self.y0_:
+                if self.y_ > self.y1_:
+                    self.y_ = round(self.clamp(
+                        self.y_ - self.step_size_, self.y1_, self.y0_), 5)
+                else:
+                    self.valid_ = False
+            else:
+                self.valid_ = False
+
+    def getX(self):
+        """Get the abscissa of the current point."""
+        return self.x_
+
+    def getY(self):
+        """Get the ordinate of the current point."""
+        return self.y_
+
+    def getX0(self):
+        """Get the abscissa of the initial point."""
+        return self.x0_
+
+    def getY0(self):
+        """Get the ordinate of the intial point."""
+        return self.y0_
+
+    def getX1(self):
+        """Get the abscissa of the final point."""
+        return self.x1_
+
+    def getY1(self):
+        """Get the ordinate of the final point."""
+        return self.y1_
+
+    def get_line_length(self):
+        """Get the length of the line."""
+        return sqrt(pow(self.x1_ - self.x0_, 2) + pow(self.y1_ - self.y0_, 2))
+
+    def clamp(self, n, min_n, max_n):
+        """
+        Clamp n to be between min_n and max_n.
+
+        Args
+        ----
+            n (float): input value
+            min_n (float): minimum value
+            max_n (float): maximum value
+
+        Returns
+        -------
+            n (float): input value clamped between given min and max
+
+        """
+        if n < min_n:
+            return min_n
+        elif n > max_n:
+            return max_n
+        else:
+            return n

nav2_simple_commander/pytest.ini

@@ -0,0 +1,2 @@
+[pytest]
+junit_family=xunit2

nav2_simple_commander/test/test_line_iterator.py

@@ -0,0 +1,107 @@
+# Copyright 2022 Afif Swaidan
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from cmath import sqrt
+import unittest
+from nav2_simple_commander.line_iterator import LineIterator
+
+
+class TestLineIterator(unittest.TestCase):
+
+    def test_type_error(self):
+        # Test if a type error raised when passing invalid arguements types
+        self.assertRaises(TypeError, LineIterator, 0, 0, '10', 10, '1')
+
+    def test_value_error(self):
+        # Test if a value error raised when passing negative or zero step_size
+        self.assertRaises(ValueError, LineIterator, 0, 0, 10, 10, -2)
+        # Test if a value error raised when passing zero length line
+        self.assertRaises(ValueError, LineIterator, 2, 2, 2, 2, 1)
+
+    def test_get_xy(self):
+        # Test if the initial and final coordinates are returned correctly
+        lt = LineIterator(0, 0, 5, 5, 1)
+        self.assertEqual(lt.getX0(), 0)
+        self.assertEqual(lt.getY0(), 0)
+        self.assertEqual(lt.getX1(), 5)
+        self.assertEqual(lt.getY1(), 5)
+
+    def test_line_length(self):
+        # Test if the line length is calculated correctly
+        lt = LineIterator(0, 0, 5, 5, 1)
+        self.assertEqual(lt.get_line_length(), sqrt(pow(5, 2) + pow(5, 2)))
+
+    def test_straight_line(self):
+        # Test if the calculations are correct for y = x
+        lt = LineIterator(0, 0, 5, 5, 1)
+        i = 0
+        while lt.isValid():
+            self.assertEqual(lt.getX(), lt.getX0() + i)
+            self.assertEqual(lt.getY(), lt.getY0() + i)
+            lt.advance()
+            i += 1
+
+        # Test if the calculations are correct for y = 2x (positive slope)
+        lt = LineIterator(0, 0, 5, 10, 1)
+        i = 0
+        while lt.isValid():
+            self.assertEqual(lt.getX(), lt.getX0() + i)
+            self.assertEqual(lt.getY(), lt.getY0() + (i*2))
+            lt.advance()
+            i += 1
+
+        # Test if the calculations are correct for y = -2x (negative slope)
+        lt = LineIterator(0, 0, 5, -10, 1)
+        i = 0
+        while lt.isValid():
+            self.assertEqual(lt.getX(), lt.getX0() + i)
+            self.assertEqual(lt.getY(), lt.getY0() + (-i*2))
+            lt.advance()
+            i += 1
+
+    def test_hor_line(self):
+        # Test if the calculations are correct for y = 0x+b (horizontal line)
+        lt = LineIterator(0, 10, 5, 10, 1)
+        i = 0
+        while lt.isValid():
+            self.assertEqual(lt.getX(), lt.getX0() + i)
+            self.assertEqual(lt.getY(), lt.getY0())
+            lt.advance()
+            i += 1
+
+    def test_ver_line(self):
+        # Test if the calculations are correct for x = n (vertical line)
+        lt = LineIterator(5, 0, 5, 10, 1)
+        i = 0
+        while lt.isValid():
+            self.assertEqual(lt.getX(), lt.getX0())
+            self.assertEqual(lt.getY(), lt.getY0() + i)
+            lt.advance()
+            i += 1
+
+    def test_clamp(self):
+        # Test if the increments are clamped to avoid crossing the final points
+        # when step_size is large with respect to line length
+        lt = LineIterator(0, 0, 5, 5, 10)
+        self.assertEqual(lt.getX(), 0)
+        self.assertEqual(lt.getY(), 0)
+        lt.advance()
+        while lt.isValid():
+            self.assertEqual(lt.getX(), 5)
+            self.assertEqual(lt.getY(), 5)
+            lt.advance()
+
+
+if __name__ == '__main__':
+    unittest.main()