allow TimeResponseData to be converted to pandas

murrayrm · murrayrm · commit e1f8d3a90f6c · 2022-04-01T21:19:49.000-07:00
diff --git a/.github/workflows/python-package-conda.yml b/.github/workflows/python-package-conda.yml
@@ -4,18 +4,20 @@ on: [push, pull_request]
 
 jobs:
   test-linux:
-    name: Python ${{ matrix.python-version }}${{ matrix.slycot && format(' with Slycot from {0}', matrix.slycot) || ' without Slycot' }}${{ matrix.array-and-matrix == 1 && ', array and matrix' || '' }}
+    name: Python ${{ matrix.python-version }}${{ matrix.slycot && format(' with Slycot from {0}', matrix.slycot) || ' without Slycot' }}${{ matrix.pandas && ', with pandas' || '' }}${{ matrix.array-and-matrix == 1 && ', array and matrix' || '' }}
     runs-on: ubuntu-latest
 
     strategy:
       max-parallel: 5
       matrix:
         python-version: [3.7, 3.9]
         slycot: ["", "conda"]
+        pandas: [""]
         array-and-matrix: [0]
         include:
           - python-version: 3.9
             slycot: conda
+            pandas: conda
             array-and-matrix: 1
 
     steps:
@@ -41,6 +43,9 @@ jobs:
         if [[ '${{matrix.slycot}}' == 'conda' ]]; then
           conda install -c conda-forge slycot
         fi
+        if [[ '${{matrix.pandas}}' == 'conda' ]]; then
+          conda install -c conda-forge pandas
+        fi
 
     - name: Test with pytest
       env:
diff --git a/control/exception.py b/control/exception.py
@@ -71,3 +71,16 @@ def slycot_check():
         except:
             slycot_installed = False
     return slycot_installed
+
+
+# Utility function to see if pandas is installed
+pandas_installed = None
+def pandas_check():
+    global pandas_installed
+    if pandas_installed is None:
+        try:
+            import pandas
+            pandas_installed = True
+        except:
+            pandas_installed = False
+    return pandas_installed
diff --git a/control/tests/timeresp_test.py b/control/tests/timeresp_test.py
@@ -9,7 +9,7 @@
 
 import control as ct
 from control import StateSpace, TransferFunction, c2d, isctime, ss2tf, tf2ss
-from control.exception import slycot_check
+from control.exception import slycot_check, pandas_check
 from control.tests.conftest import slycotonly
 from control.timeresp import (_default_time_vector, _ideal_tfinal_and_dt,
                               forced_response, impulse_response,
@@ -1180,3 +1180,55 @@ def test_response_transpose(
         assert t.shape == (T.size, )
         assert y.shape == ysh_no
         assert x.shape == (T.size, sys.nstates)
+
+
+@pytest.mark.skipif(not pandas_check(), reason="pandas not installed")
+def test_to_pandas():
+    # Create a SISO time response
+    sys = ct.rss(2, 1, 1)
+    timepts = np.linspace(0, 10, 10)
+    resp = ct.input_output_response(sys, timepts, 1)
+
+    # Convert to pandas
+    df = resp.to_pandas()
+
+    # Check to make sure the data make senses
+    np.testing.assert_equal(df['time'], resp.time)
+    np.testing.assert_equal(df['u[0]'], resp.inputs)
+    np.testing.assert_equal(df['y[0]'], resp.outputs)
+    np.testing.assert_equal(df['x[0]'], resp.states[0])
+    np.testing.assert_equal(df['x[1]'], resp.states[1])
+
+    # Create a MIMO time response
+    sys = ct.rss(2, 2, 1)
+    resp = ct.input_output_response(sys, timepts, np.sin(timepts))
+    df = resp.to_pandas()
+    np.testing.assert_equal(df['time'], resp.time)
+    np.testing.assert_equal(df['u[0]'], resp.inputs[0])
+    np.testing.assert_equal(df['y[0]'], resp.outputs[0])
+    np.testing.assert_equal(df['y[1]'], resp.outputs[1])
+    np.testing.assert_equal(df['x[0]'], resp.states[0])
+    np.testing.assert_equal(df['x[1]'], resp.states[1])
+
+    # Change the time points
+    sys = ct.rss(2, 1, 1)
+    T = np.linspace(0, timepts[-1]/2, timepts.size * 2)
+    resp = ct.input_output_response(sys, timepts, np.sin(timepts), t_eval=T)
+    df = resp.to_pandas()
+    np.testing.assert_equal(df['time'], resp.time)
+    np.testing.assert_equal(df['u[0]'], resp.inputs)
+    np.testing.assert_equal(df['y[0]'], resp.outputs)
+    np.testing.assert_equal(df['x[0]'], resp.states[0])
+    np.testing.assert_equal(df['x[1]'], resp.states[1])
+
+
+@pytest.mark.skipif(pandas_check(), reason="pandas installed")
+def test_no_pandas():
+    # Create a SISO time response
+    sys = ct.rss(2, 1, 1)
+    timepts = np.linspace(0, 10, 10)
+    resp = ct.input_output_response(sys, timepts, 1)
+
+    # Convert to pandas
+    with pytest.raises(ImportError, match="pandas"):
+        df = resp.to_pandas()
diff --git a/control/timeresp.py b/control/timeresp.py
@@ -79,6 +79,7 @@
 from copy import copy
 
 from . import config
+from .exception import pandas_check
 from .lti import isctime, isdtime
 from .statesp import StateSpace, _convert_to_statespace, _mimo2simo, _mimo2siso
 from .xferfcn import TransferFunction
@@ -638,6 +639,23 @@ def __getitem__(self, index):
     def __len__(self):
         return 3 if self.return_x else 2
 
+    # Convert to pandas
+    def to_pandas(self):
+        if not pandas_check():
+            ImportError('pandas not installed')
+        import pandas
+
+        # Create a dict for setting up the data frame
+        data = {'time': self.time}
+        data.update(
+            {name: self.u[i] for i, name in enumerate(self.input_labels)})
+        data.update(
+            {name: self.y[i] for i, name in enumerate(self.output_labels)})
+        data.update(
+            {name: self.x[i] for i, name in enumerate(self.state_labels)})
+
+        return pandas.DataFrame(data)
+
 
 # Process signal labels
 def _process_labels(labels, signal, length):
