Added interpolator and implemented correct parsing and output for JavaProp to JSBsim CP and CT tables converter

README.md

@@ -1,2 +1,20 @@
-# fgscenery-tools
+# fgtools
-Tools for creating, managing and editing FlightGear scenery
+Tools for creating, managing and editing FlightGear scenery, aircraft, …
+
+## Installation
+To run these scripts you need Python 3, Python 2 won't work. Recommended version is 3.8 as I only have that installed so couldn't test with any other versions - earlier 3.x versions should work, but no guarantee !
+
+### Linux
+Download / `git clone` this repo and put it in a place of your choice, say `/home/user/fgtools`. With `git clone`, you would use this command:
+```sh
+/home/user$ git clone https://github.com/TheFGFSEagle/fgtools
+```
+Before you run the scripts you have to make sure that the folder containing this repository on your local disk (here `/home/user`) is inside your `PYTHONPATH` environment variable, or you must run the scripts from inside the `fgtools` folder. To add the folder to your `PYTHONPATH`, use this command:
+```sh
+export PYTHONPATH="${PYTHONPATH}:/home/user"
+```
+Note: this is lost when you close the terminal / console, so you have to run this command every time you open a new console and run the scripts from it. To make the change persistent, add the command to the end of the `.profile` file in your home folder.
+
+### Windows
+_I don't have Windows so cannot provide any instructions - contributions by Windows users welcome !_
+

aircraft/javaprop2jsbcpct.py

@@ -3,24 +3,51 @@
 
 import argparse
 import os
+from fgtools.utils.interpolator import Interpolator
+
 
 def parse_data_files(input_files, blade_angles):
 	blade_angles = list(map(float, blade_angles))
 	data = {}
 	for file, angle in zip(input_files, blade_angles):
+		data[angle] = {
+			"Cp": Interpolator(),
+			"Ct": Interpolator()
+		}
 		with open(file) as f:
 			content = f.readlines()
 		
 		content = list(map(lambda s: s.strip().split("\t"), content))[2:]
-		data[angle] = {}
 		for line in content:
-			data[angle][float(line[0])] = {"Ct": float(line[2]), "Cp": float(line[3])}
+			av, cp, ct = float(line[0]), float(line[2]), float(line[3])
+			data[angle]["Cp"].add_value(av, cp)
+			data[angle]["Ct"].add_value(av, ct)
 	
 	return data
 
 
+def make_tables(data, maximum, indentation="\t", resolution=0.05):
+	Cp = Ct = indentation * 4 + (indentation * 2).join(map(str, data)) + "\n"
+	av = 0
+	while av <= maximum:
+		av = round(av, 6)
+		Cp += indentation * 2 + indentation + str(av) + indentation
+		Ct += indentation * 2 + indentation + str(av) + indentation
+		cps = []
+		cts = []
+		for angle in data:
+			cps.append("%.6f" % round(data[angle]["Cp"].interpolate(av, sort=False), 6))
+			cts.append("%.6f" % round(data[angle]["Ct"].interpolate(av, sort=False), 6))
+		
+		Cp += indentation.join(cps) + "\n"
+		Ct += indentation.join(cts) + "\n"
+		av += resolution
+	return {"Cp":Cp, "Ct": Ct}		
+				
+
+
 if __name__ == "__main__":
-	argp = argparse.ArgumentParser(description="javaprop2jsbcpct.py - converts JavaProp propeller data into Cp and Ct tables for a JSBsim propelller")
+	argp = argparse.ArgumentParser(description="javaprop2jsbcpct.py - converts JavaProp propeller data into Cp and Ct tables for a JSBsim propeller")
 	
 	argp.add_argument(
 		"-i", "--input-file",
@@ -38,6 +65,13 @@ if __name__ == "__main__":
 		dest="blade_angles"
 	)
 	
+	argp.add_argument(
+		"-m", "--max",
+		help="Maximum advance ratio to output data for",
+		required=True,
+		type=float
+	)
+	
 	argp.add_argument(
 		"--interactive",
 		action="store_true",
@@ -50,6 +84,13 @@ if __name__ == "__main__":
 		default="\t"
 	)
 	
+	argp.add_argument(
+		"-r", "--resolution",
+		help="Advance ratio resolution to generate (default: 0.05)",
+		type=float,
+		default=0.05
+	)
+	
 	args = argp.parse_args()
 	
 	for path in args.input_files:
@@ -60,8 +101,22 @@ if __name__ == "__main__":
 	if len(args.blade_angles) < len(args.input_files):
 		print("Error: less blade angles than input files")
 	elif len(args.blade_angles) > len(args.input_files):
-		args.blade_angles, rest = args.blade_angles[:len(args.input_files)]
+		args.blade_angles, rest = args.blade_angles[:len(args.input_files) + 1]
 		print(f"Warning: skipping {len(rest)} blade angles because no corresponding data file was specified")
 	
 	data = parse_data_files(args.input_files, args.blade_angles)
+	output = make_tables(data, args.max, args.indentation, args.resolution)
+	
+	
+	print(args.indentation + "<table name=\"C_THRUST\" type=\"internal\">")
+	print(args.indentation * 2 + "<tableData>")
+	print(output["Ct"])
+	print(args.indentation * 2 + "</tableData>")
+	print(args.indentation + "</table>")
+	print(args.indentation)
+	print(args.indentation + "<table name=\"C_POWER\" type=\"internal\">")
+	print(args.indentation * 2 + "<tableData>")
+	print(output["Cp"])
+	print(args.indentation * 2 + "</tableData>")
+	print(args.indentation + "</table>")
 

utils/interpolator.py

@@ -0,0 +1,82 @@
+#!/usr/bin/env python
+#-*- coding:utf-8 -*-
+
+class Interpolator:
+	def __init__(self):
+		self._indexes = []
+		self._values = []
+		self._sorted = False
+		
+		self.methods = {"linear": self._interpolate_linear}
+	
+	def add_value(self, index, value):
+		if type(index) not in (int, float) or type(value) not in (int, float):
+			try:
+				index = float(index)
+				value = float(value)
+			except ValueError:
+				raise TypeError(f"Interpolator.add_value: index '{index}' or value '{value}' not a number")
+		
+		self._indexes.append(index)
+		self._values.append(value)
+		self._sorted = False
+	
+	def add_values(self, indexes, values):
+		for i, v in zip(indexes, values):
+			self.add_value(i, v)
+	
+	def interpolate(self, index, extrapolate=True, method="linear", sort=True):
+		if not method in self.methods:
+			raise NotImplementedError(f"Interpolator.interpolate: interpolation method '{method}' not yet supported")
+		
+		if len(self._indexes) < 2:
+			raise ValueError(f"Interpolator.interpolate: cannot interpolate on a table with less than two data points")
+		
+		# only sort if not already sorted to increase performance for large tables
+		if not self._sorted and sort:
+			self._indexes.sort()
+			self._values.sort()
+			self._sorted = True
+		
+		return self.methods[method](index, extrapolate)
+	
+	def _find_neighbours(self, index):
+		lower = upper = 0
+		last = self._indexes[0]
+		for it, _index in enumerate(self._indexes):
+			lower = last
+			last = it
+			if _index > index:
+				upper = it
+				break
+		
+		return lower, upper
+	
+	def _interpolate_linear(self, index, extrapolate=True):
+		if index in self._indexes:
+			return self._values[self._indexes.index(index)]
+		
+		if self._indexes[0] < index < self._indexes[-1]:
+			lower, upper = self._find_neighbours(index)
+			return self._values[lower] + (self._values[upper] - self._values[lower]) * (index - self._indexes[lower]) / (self._indexes[upper] - self._indexes[lower]) 
+		else:
+			if not extrapolate:
+				if index < self._indexes[0]:
+					return self._values[0]
+				else:
+					return self._values[-1]
+			else:
+				if index < self._indexes[0]:
+					return self._values[1] + (index - self._indexes[1]) / (self._indexes[0] - self._indexes[1]) * (self._values[0] - self._values[1])
+				else:
+					return self._values[-2] + (index - self._indexes[-2]) / (self._indexes[-1] - self._indexes[-2]) * (self._values[-1] - self._values[-2])
+
+# run test if run directly
+if __name__ == "__main__":
+	print("Test results")
+	i = Interpolator()
+	i.add_values((0, 10, 20), (0, 20, 30))
+	for test_val in (-5, 0, 1, 2, 3.5, 5.55555, 9, 10, 15, 100):
+		print(test_val, i.interpolate(test_val))
+	
+