Add Central filtrering.

include/DigitalFilter.h

@@ -50,6 +50,35 @@ public:
         : GenericFilter<T>(aCoeff, bCoeff)
     {
     }
+    void setCoefficients(vectX_t<T>&& aCoeff, vectX_t<T>&& bCoeff)
+    {
+        setCoeffs(std::forward(aCoeff), std::forward(bCoeff));
+    }
+};
+
+/*! \brief Basic centered digital filter.
+ * 
+ * This filter allows you to set any centered digital filter based on its coefficients.
+ * \tparam T Floating type.
+ */
+template <typename T>
+class CenteredDigitalFilter : public GenericFilter<T> {
+public:
+    /*! \brief Default uninitialized constructor. */
+    CenteredDigitalFilter() = default;
+    /*! \brief Constructor.
+     * \param aCoeff Denominator coefficients of the filter in decreasing order.
+     * \param bCoeff Numerator coefficients of the filter in decreasing order.
+     */
+    CenteredDigitalFilter(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff)
+        : GenericFilter<T>(aCoeff, bCoeff, Type::Centered)
+    {
+    }
+    void setCoefficients(vectX_t<T>&& aCoeff, vectX_t<T>&& bCoeff)
+    {
+        setCoeffs(std::forward(aCoeff), std::forward(bCoeff));
+        setType(Type::Centered);
+    }
 };
 
 } // namespace difi

include/GenericFilter.h

@@ -35,6 +35,9 @@
 
 namespace difi {
 
+// TODO: noexcept(Function of gsl variable)
+// TODO: constructor with universal refs
+
 /*! \brief Low-level filter.
  * 
  * It creates the basic and common functions of all linear filter that can written as a digital filter.
@@ -49,6 +52,12 @@ template <typename T>
 class GenericFilter {
     static_assert(std::is_floating_point<T>::value && !std::is_const<T>::value, "Only accept non-complex floating point types.");
 
+public:
+    enum class Type {
+        OneSided,
+        Centered
+    };
+
 public:
     /*! \brief Filter a new data.
      * 
@@ -64,16 +73,11 @@ public:
      * \return Filtered signal.
      */
     vectX_t<T> filter(const vectX_t<T>& data);
-    /*! \brief Filter a signal and store in a user-defined Eigen vector.
-     * 
-     * Useful if the length of the signal is known in advance.
-     * \param[out] results Filtered signal.
-     * \param data Signal.
-     * \return False if vector's lengths do not match.
-     */
-    void getFilterResults(Eigen::Ref<vectX_t<T>> results, const vectX_t<T>& data);
     /*! \brief Reset the data and filtered data. */
     void resetFilter() noexcept;
+
+    /*!< \brief Return the filter type */
+    Type type() const noexcept { return (m_center == 0 ? Type::OneSided : Type::Centered); }
     /*! \brief Get digital filter coefficients.
      * 
      * It will automatically resize the given vectors.
@@ -81,6 +85,10 @@ public:
      * \param[out] bCoeff Numerator coefficients of the filter in decreasing order.
      */
     void getCoeffs(vectX_t<T>& aCoeff, vectX_t<T>& bCoeff) const noexcept;
+    /*! \brief Return coefficients of the denominator polynome. */
+    const vectX_t<T>& aCoeff() const noexcept { return m_aCoeff; }
+    /*! \brief Return coefficients of the numerator polynome. */
+    const vectX_t<T>& bCoeff() const noexcept { return m_bCoeff; }
     /*! \brief Return the order the denominator polynome order of the filter. */
     Eigen::Index aOrder() const noexcept { return m_aCoeff.size(); }
     /*! \brief Return the order the numerator polynome order of the filter. */
@@ -94,11 +102,18 @@ protected:
     /*! \brief Constructor.
      * \param aCoeff Denominator coefficients of the filter in decreasing order.
      * \param bCoeff Numerator coefficients of the filter in decreasing order.
+     * \param center 
      */
-    GenericFilter(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff);
+    GenericFilter(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff, Type type = Type::OneSided);
     /*! \brief Default destructor. */
     virtual ~GenericFilter() = default;
 
+    /*! \brief Set type of filter (one-sided or centered)
+     * 
+     * \param type The filter type.
+     * \warning bCoeff must be set before.
+     */
+    void setType(Type type);
     /*! \brief Set the new coefficients of the filters.
      *
      * It awaits a universal reference.
@@ -116,9 +131,10 @@ protected:
      * \param bCoeff Numerator coefficients of the filter.
      * \return True if the filter status is set on READY.
      */
-    void checkCoeffs(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff);
+    bool checkCoeffs(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff, Type type);
 
 private:
+    Eigen::Index m_center = 0; /*!< Center of the filter. 0 is a one-sided filter. Default is 0. */
     bool m_isInitialized = false; /*!< Initialization state of the filter. Default is false */
     vectX_t<T> m_aCoeff; /*!< Denominator coefficients of the filter */
     vectX_t<T> m_bCoeff; /*!< Numerator coefficients of the filter */

include/GenericFilter.tpp

@@ -44,25 +44,18 @@ T GenericFilter<T>::stepFilter(const T& data)
 
     m_rawData[0] = data;
     m_filteredData[0] = 0;
-    m_filteredData[0] = m_bCoeff.dot(m_rawData) - m_aCoeff.dot(m_filteredData);
+    m_filteredData[m_center] = m_bCoeff.dot(m_rawData) - m_aCoeff.dot(m_filteredData);
-    return m_filteredData[0];
+    return m_filteredData[m_center];
 }
 
 template <typename T>
 vectX_t<T> GenericFilter<T>::filter(const vectX_t<T>& data)
-{
-    vectX_t<T> results(data.size());
-    getFilterResults(results, data);
-    return results;
-}
-
-template <typename T>
-void GenericFilter<T>::getFilterResults(Eigen::Ref<vectX_t<T>> results, const vectX_t<T>& data)
 {
     Expects(m_isInitialized);
-    Expects(results.size() == data.size());
+    vectX_t<T> results(data.size());
     for (Eigen::Index i = 0; i < data.size(); ++i)
         results(i) = stepFilter(data(i));
+    return results;
 }
 
 template <typename T>
@@ -72,13 +65,20 @@ void GenericFilter<T>::resetFilter() noexcept
     m_rawData.setZero(m_bCoeff.size());
 }
 
+template <typename T>
+void GenericFilter<T>::setType(Type type)
+{
+    Expects(type == Type::Centered ? m_bCoeff.size() > 2 && m_bCoeff.size() % 2 == 1 : true);
+    m_center = (type == Type::OneSided ? 0 : (m_bCoeff.size() - 1) / 2);
+}
+
 template <typename T>
 template <typename T2>
 void GenericFilter<T>::setCoeffs(T2&& aCoeff, T2&& bCoeff)
 {
     static_assert(std::is_convertible_v<T2, vectX_t<T>>, "The coefficients types should be convertible to vectX_t<T>");
 
-    checkCoeffs(aCoeff, bCoeff);
+    Expects(checkCoeffs(aCoeff, bCoeff, (m_center == 0 ? Type::OneSided : Type::Centered)));
     m_aCoeff = aCoeff;
     m_bCoeff = bCoeff;
     normalizeCoeffs();
@@ -96,13 +96,14 @@ void GenericFilter<T>::getCoeffs(vectX_t<T>& aCoeff, vectX_t<T>& bCoeff) const n
 // Protected functions
 
 template <typename T>
-GenericFilter<T>::GenericFilter(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff)
+GenericFilter<T>::GenericFilter(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff, Type type)
     : m_aCoeff(aCoeff)
     , m_bCoeff(bCoeff)
     , m_filteredData(aCoeff.size())
     , m_rawData(bCoeff.size())
 {
-    checkCoeffs(aCoeff, bCoeff);
+    Expects(checkCoeffs(aCoeff, bCoeff, type));
+    m_center = (type == Type::OneSided ? 0 : (bCoeff.size() - 1) / 2);
     normalizeCoeffs();
     resetFilter();
     m_isInitialized = true;
@@ -120,11 +121,10 @@ void GenericFilter<T>::normalizeCoeffs()
 }
 
 template <typename T>
-void GenericFilter<T>::checkCoeffs(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff)
+bool GenericFilter<T>::checkCoeffs(const vectX_t<T>& aCoeff, const vectX_t<T>& bCoeff, Type type)
 {
-    Expects(aCoeff.size() > 0);
+    bool centering = (type == Type::Centered ? (bCoeff.size() % 2 == 1) : true);
-    Expects(std::abs(aCoeff[0]) > std::numeric_limits<T>::epsilon());
+    return aCoeff.size() > 0 && std::abs(aCoeff[0]) > std::numeric_limits<T>::epsilon() && bCoeff.size() > 0 && centering;
-    Expects(bCoeff.size() > 0);
 }
 
 } // namespace difi

include/MovingAverage.h

@@ -60,4 +60,32 @@ public:
     int windowSize() const noexcept { return bOrder(); }
 };
 
+/*! \brief Centered moving average digital filter.
+ * 
+ * This is a specialization of a digital filter in order to use a centered moving average.
+ * \tparam T Floating type.
+ */
+template <typename T>
+class CenteredMovingAverage : public DigitalFilter<T> {
+public:
+    /*! \brief Default uninitialized constructor. */
+    CenteredMovingAverage() = default;
+    /*! \brief Constructor.
+     * \param windowSize Size of the moving average window.
+     */
+    CenteredMovingAverage(int windowSize)
+    {
+        setWindowSize(windowSize);
+    }
+    /*! \brief Set the size of the moving average window. */
+    void setWindowSize(int windowSize)
+    {
+        Expects(windowSize > 2 && windowSize % 2 == 1);
+        setCoeffs(vectX_t<T>::Constant(1, T(1)), vectX_t<T>::Constant(windowSize, T(1) / windowSize));
+        setType(Type::Centered);
+    }
+    /*! \brief Get the size of the moving average window. */
+    int windowSize() const noexcept { return bOrder(); }
+};
+
 } // namespace difi