BUG: Function breaks if a header is present in the csv file

CHANGELOG.md

@@ -42,12 +42,18 @@ straightforward as possible.
 
 -
 
+## [v1.1.2] - 2023-11-25
+
+You can install this version by running `pip install rocketpy==1.1.2`
+
+### Fixed
+
+- BUG: Function breaks if a header is present in the csv file [#485](https://github.com/RocketPy-Team/RocketPy/pull/485)
 
 ## [v1.1.1] - 2023-11-23
 
 You can install this version by running `pip install rocketpy==1.1.1`
 
-
 ### Added
 
 - DOC: Added this changelog file [#472](https://github.com/RocketPy-Team/RocketPy/pull/472)

docs/user/motors/liquidmotor.rst

@@ -40,15 +40,15 @@ Then we must first define the tanks:
   fuel_gas = Fluid(name="ethanol_g", density=1.59)
 
   # Define tanks geometry
-  tanks_shape = CylindricalTank(radius = 0.1, height = 1, spherical_caps = True)
+  tanks_shape = CylindricalTank(radius = 0.1, height = 1.2, spherical_caps = True)
 
   # Define tanks
   oxidizer_tank = MassFlowRateBasedTank(
       name="oxidizer tank",
       geometry=tanks_shape,
       flux_time=5,
       initial_liquid_mass=32,
-      initial_gas_mass=0.1,
+      initial_gas_mass=0.01,
       liquid_mass_flow_rate_in=0,
       liquid_mass_flow_rate_out=lambda t: 32 / 3 * exp(-0.25 * t),
       gas_mass_flow_rate_in=0,

rocketpy/mathutils/function.py

@@ -39,14 +39,9 @@
 
         Parameters
         ----------
-        source : function, scalar, ndarray, string
-            The actual function. If type is function, it will be called for
-            evaluation. If type is int or float, it will be treated as a
-            constant function. If ndarray, its points will be used for
-            interpolation. An ndarray should be as [(x0, y0, z0), (x1, y1, z1),
-            (x2, y2, z2), ...] where x0 and y0 are inputs and z0 is output. If
-            string, imports file named by the string and treats it as csv.
-            The file is converted into ndarray and should not have headers.
+        source : function, scalar, ndarray, string, Function
+            The data source to be used for the function. See the ``set_source``
+            method's documentation for more details.
         inputs : string, sequence of strings, optional
             The name of the inputs of the function. Will be used for
             representation and graphing (axis names). 'Scalar' is default.
@@ -133,25 +128,39 @@
         return self
 
     def set_source(self, source):
-        """Set the source which defines the output of the function giving a
-        certain input.
+        """Sets the data source for the function, defining how the function
+        produces output from a given input.
 
         Parameters
         ----------
-        source : function, scalar, ndarray, string, Function
-            The actual function. If type is function, it will be called for
-            evaluation. If type is int or float, it will be treated as a
-            constant function. If ndarray, its points will be used for
-            interpolation. An ndarray should be as [(x0, y0, z0), (x1, y1, z1),
-            (x2, y2, z2), ...] where x0 and y0 are inputs and z0 is output. If
-            string, imports file named by the string and treats it as csv.
-            The file is converted into ndarray and should not have headers.
-            If the source is a Function, its source will be copied and another
-            Function will be created following the new inputs and outputs.
+        source : function, scalar, ndarray, string, or Function
+            The data source to be used for the function:
+
+            - Python function: Called for evaluation with input values.
+
+            - int or float: Treated as a constant value.
+
+            - ndarray: Used for interpolation. Format as [(x0, y0, z0),
+            (x1, y1, z1), ..., (xn, yn, zn)], where 'x' and 'y' are inputs,
+            and 'z' is the output.
+
+            - string: Path to a CSV file. The file is read and converted into an
+            ndarray. The file can optionally contain a single header line.
+
+            - Function: Copies the source of the provided Function object,
+            creating a new Function with adjusted inputs and outputs.
+
+        Notes
+        -----
+        (I) CSV files can optionally contain a single header line. If present,
+        the header is ignored during processing.
+        (II) Fields in CSV files may be enclosed in double quotes. If fields are
+        not quoted, double quotes should not appear inside them.
 
         Returns
         -------
         self : Function
+            Returns the Function instance.
         """
         _ = self._check_user_input(
             source,
@@ -165,20 +174,20 @@
             source = source.get_source()
         # Import CSV if source is a string or Path and convert values to ndarray
         if isinstance(source, (str, Path)):
-            # Read file and check for headers
-            with open(source, mode="r") as f:
-                first_line = f.readline()
-            # If headers are found...
-            if first_line[0] in ['"', "'"]:
-                # Headers available
-                first_line = first_line.replace('"', " ").replace("'", " ")
-                first_line = first_line.split(" , ")
-                self.set_inputs(first_line[0])
-                self.set_outputs(first_line[1:])
-                source = np.loadtxt(source, delimiter=",", skiprows=1, dtype=float)
-            # if headers are not found
-            else:
-                source = np.loadtxt(source, delimiter=",", dtype=float)
+            with open(source, "r") as file:
+                first_line = file.readline()
+                try:
+                    # Try to convert the first line to floats
+                    np.array([float(item) for item in first_line.split(",")])
+                    # If successful, no headers are present
+                    file.seek(0)  # Reset file read position
+                    source = np.loadtxt(file, delimiter=",", dtype=float)
+                except ValueError:
+                    # If an error occurs, headers are present
+                    source = np.genfromtxt(
+                        source, delimiter=",", dtype=float, skip_header=1
+                    )
+
         # Convert to ndarray if source is a list
         if isinstance(source, (list, tuple)):
             source = np.array(source, dtype=np.float64)
@@ -2830,7 +2839,15 @@
             # Deal with csv or txt
             if isinstance(source, (str, Path)):
                 # Convert to numpy array
-                source = np.loadtxt(source, delimiter=",", dtype=float)
+                try:
+                    source = np.loadtxt(source, delimiter=",", dtype=float)
+                except ValueError:
+                    # Skip header
+                    source = np.loadtxt(source, delimiter=",", dtype=float, skiprows=1)
+                except Exception as e:
+                    raise ValueError(
+                        "The source file is not a valid csv or txt file."
+                    ) from e
 
             else:
                 # this will also trigger an error if the source is not a list of

tests/fixtures/function/1d_no_quotes.csv

@@ -0,0 +1,4 @@
+time,value
+0,100
+1,200
+2,300

tests/fixtures/function/1d_quotes.csv

@@ -0,0 +1,4 @@
+"time","value"
+0,100
+1,200
+2,300

tests/test_function.py

@@ -37,6 +37,23 @@ def test_function_from_csv(func_from_csv, func_2d_from_csv):
     )
 
 
+@pytest.mark.parametrize(
+    "csv_file",
+    [
+        "tests/fixtures/function/1d_quotes.csv",
+        "tests/fixtures/function/1d_no_quotes.csv",
+    ],
+)
+def test_func_from_csv_with_header(csv_file):
+    """Tests if a Function can be created from a CSV file with a single header
+    line. It tests cases where the fields are separated by quotes and without
+    quotes."""
+    f = Function(csv_file)
+    assert f.__repr__() == "'Function from R1 to R1 : (Scalar) → (Scalar)'"
+    assert np.isclose(f(0), 100)
+    assert np.isclose(f(0) + f(1), 300), "Error summing the values of the function"
+
+
 def test_getters(func_from_csv, func_2d_from_csv):
     """Test the different getters of the Function class.