Refactor createCSVData

I found the old code really hard to understand, so I decided to rewrite
it from scratch. It should behave exactly the same (and the tests in
test_ModelicaSystem prove that).

Author: ondras12345

OMPython/ModelicaSystem.py

@@ -801,112 +801,52 @@ def checkValidInputs(self, name):
             else:
                 ModelicaSystemError('Error!!! Value must be in tuple format')
 
-    # To create csv file for inputs
-    def createCSVData(self):
-        sl = []  # Actual timestamps
-        skip = False
-
-        # check for NONE in input list and replace with proper data (e.g) [(startTime, 0.0), (stopTime, 0.0)]
-        tmpinputlist = {}
-        for key, value in self.inputlist.items():
-            if value is None:
-                tmpinputlist[key] = [(float(self.simulateOptions["startTime"]), 0.0),
-                                     (float(self.simulateOptions["stopTime"]), 0.0)]
+    def createCSVData(self) -> None:
+        start_time: float = float(self.simulateOptions["startTime"])
+        stop_time: float = float(self.simulateOptions["stopTime"])
+
+        # Replace None inputs with a default constant zero signal
+        inputs: dict[str, list[tuple[float, float]]] = {}
+        for input_name, input_signal in self.inputlist.items():
+            if input_signal is None:
+                inputs[input_name] = [(start_time, 0.0), (stop_time, 0.0)]
             else:
-                tmpinputlist[key] = value
-
-        inp = list(tmpinputlist.values())
-
-        for i in inp:
-            cl = list()
-            el = list()
-            for t, x in i:
-                cl.append(t)
-            for i in cl:
-                if skip is True:
-                    skip = False
-                    continue
-                if i not in sl:
-                    el.append(i)
-                else:
-                    elem_no = cl.count(i)
-                    sl_no = sl.count(i)
-                    if elem_no == 2 and sl_no == 1:
-                        el.append(i)
-                        skip = True
-            sl = sl + el
-
-        sl.sort()
-        for t in sl:
-            for i in inp:
-                for ttt in [tt[0] for tt in i]:
-                    if t not in [tt[0] for tt in i]:
-                        i.append((t, '?'))
-        inpSortedList = list()
-        sortedList = list()
-        for i in inp:
-            sortedList = sorted(i, key=lambda x: x[0])
-            inpSortedList.append(sortedList)
-        for i in inpSortedList:
-            ind = 0
-            for t, x in i:
-                if x == '?':
-                    t1 = i[ind - 1][0]
-                    u1 = i[ind - 1][1]
-                    t2 = i[ind + 1][0]
-                    u2 = i[ind + 1][1]
-                    nex = 2
-                    while (u2 == '?'):
-                        u2 = i[ind + nex][1]
-                        t2 = i[ind + nex][0]
-                        nex += 1
-                    x = float(u1 + (u2 - u1) * (t - t1) / (t2 - t1))
-                    i[ind] = (t, x)
-                ind += 1
-        slSet = list()
-        slSet = set(sl)
-        for i in inpSortedList:
-            tempTime = list()
-            for (t, x) in i:
-                tempTime.append(t)
-            inSl = None
-            inI = None
-            for s in slSet:
-                inSl = sl.count(s)
-                inI = tempTime.count(s)
-                if inSl != inI:
-                    test = list()
-                    test = [(x, y) for x, y in i if x == s]
-                    i.append(test[0])
-        newInpList = list()
-        tempSorting = list()
-        for i in inpSortedList:
-            # i.sort() => just sorting might not work so need to sort according to 1st element of a tuple
-            tempSorting = sorted(i, key=lambda x: x[0])
-            newInpList.append(tempSorting)
-
-        interpolated_inputs_all = list()
-        for i in newInpList:
-            templist = list()
-            for (t, x) in i:
-                templist.append(x)
-            interpolated_inputs_all.append(templist)
-
-        name = ','.join(list(self.inputlist.keys()))
-        name = f'time,{name},end'
-
-        a = ''
-        l = []
-        l.append(name)
-        for i in range(0, len(sl)):
-            a = f'{float(sl[i])},{",".join(str(float(inppp[i])) for inppp in interpolated_inputs_all)},0'
-            l.append(a)
-
-        self.csvFile = (pathlib.Path(self.tempdir) / f'{self.modelName}.csv').as_posix()
+                inputs[input_name] = input_signal
+
+        # Collect all unique timestamps across all input signals
+        all_times = np.array(
+            sorted({t for signal in inputs.values() for t, _ in signal}),
+            dtype=float
+        )
+
+        # Interpolate missing values
+        interpolated_inputs: dict[str, np.ndarray] = {}
+        for signal_name, signal_values in inputs.items():
+            signal = np.array(signal_values)
+            interpolated_inputs[signal_name] = np.interp(
+                all_times,
+                signal[:, 0],  # times
+                signal[:, 1]  # values
+            )
+
+        # Write CSV file
+        input_names = list(interpolated_inputs.keys())
+        header = ['time'] + input_names + ['end']
+
+        csv_rows = [header]
+        for i, t in enumerate(all_times):
+            row = [
+                t,  # time
+                *(interpolated_inputs[name][i] for name in input_names),  # input values
+                0  # trailing 'end' column
+            ]
+            csv_rows.append(row)
+
+        self.csvFile: str = (pathlib.Path(self.tempdir) / f'{self.modelName}.csv').as_posix()
+
         with open(self.csvFile, "w", newline="") as f:
-            writer = csv.writer(f, delimiter='\n')
-            writer.writerow(l)
-        f.close()
+            writer = csv.writer(f)
+            writer.writerows(csv_rows)
 
     # to convert Modelica model to FMU
     def convertMo2Fmu(self, version="2.0", fmuType="me_cs", fileNamePrefix="<default>", includeResources=True):  # 19