Add file to generate example data

gui/gen_example_data.py

@@ -0,0 +1,17 @@
+import pandas as pd
+import numpy as np
+
+rand_between = lambda a, b, size: np.random.rand(*size) * (b - a) + a
+
+X = pd.DataFrame(
+    {
+        "T": rand_between(273, 373, (100,)),  # Kelvin
+        "P": rand_between(100, 200, (100,)) * 1e3,  # Pa
+        "n": rand_between(0, 10, (100,)),  # mole
+    }
+)
+
+R = 8.3144598  # J/mol/K
+X["y"] = X["n"] * R * X["T"] / X["P"]
+
+X.to_csv("data.csv", index=False)