#6007 Add utility for linear interpolation.

ApplicationCode/Application/Tools/CMakeLists_files.cmake

@@ -16,6 +16,7 @@ ${CMAKE_CURRENT_LIST_DIR}/RiaQDateTimeTools.h
 ${CMAKE_CURRENT_LIST_DIR}/RiaSummaryTools.h
 ${CMAKE_CURRENT_LIST_DIR}/RiaWellNameComparer.h
 ${CMAKE_CURRENT_LIST_DIR}/RiaStdStringTools.h
+${CMAKE_CURRENT_LIST_DIR}/RiaInterpolationTools.h
 ${CMAKE_CURRENT_LIST_DIR}/RiaSummaryCurveAnalyzer.h
 ${CMAKE_CURRENT_LIST_DIR}/RiaSimWellBranchTools.h
 ${CMAKE_CURRENT_LIST_DIR}/RiaProjectFileVersionTools.h
@@ -62,6 +63,7 @@ ${CMAKE_CURRENT_LIST_DIR}/RiaQDateTimeTools.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaSummaryTools.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaWellNameComparer.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaStdStringTools.cpp
+${CMAKE_CURRENT_LIST_DIR}/RiaInterpolationTools.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaSummaryCurveAnalyzer.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaSimWellBranchTools.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaProjectFileVersionTools.cpp

ApplicationCode/Application/Tools/RiaInterpolationTools.cpp

@@ -0,0 +1,66 @@
+/////////////////////////////////////////////////////////////////////////////////
+//
+//  Copyright (C) 2020     Equinor ASA
+//
+//  ResInsight is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
+//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+//  FITNESS FOR A PARTICULAR PURPOSE.
+//
+//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
+//  for more details.
+//
+/////////////////////////////////////////////////////////////////////////////////
+
+#include "RiaInterpolationTools.h"
+
+#include <cassert>
+#include <limits>
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+double RiaInterpolationTools::linear( const std::vector<double>& x, const std::vector<double>& y, double value )
+{
+    assert( x.size() == y.size() );
+
+    // Handle cases with only one data point.
+    if ( x.size() == 1 )
+    {
+        return std::numeric_limits<double>::infinity();
+    }
+
+    // Find the lower boundary
+    bool found      = false;
+    int  lowerIndex = 0;
+    for ( int i = 0; i < static_cast<int>( x.size() - 1 ); i++ )
+    {
+        if ( x[i] < value && x[i + 1] > value )
+        {
+            lowerIndex = i;
+            found      = true;
+        }
+    }
+
+    // Value is outside of the defined range
+    if ( !found )
+    {
+        return std::numeric_limits<double>::infinity();
+    }
+
+    int upperIndex = lowerIndex + 1;
+
+    double lowerX = x[lowerIndex];
+    double lowerY = y[lowerIndex];
+    double upperX = x[upperIndex];
+    double upperY = y[upperIndex];
+
+    double deltaY = upperY - lowerY;
+    double deltaX = upperX - lowerX;
+
+    return lowerY + ( ( value - lowerX ) / deltaX ) * deltaY;
+}

ApplicationCode/Application/Tools/RiaInterpolationTools.h

@@ -0,0 +1,30 @@
+/////////////////////////////////////////////////////////////////////////////////
+//
+//  Copyright (C) 2020     Equinor ASA
+//
+//  ResInsight is free software: you can redistribute it and/or modify
+//  it under the terms of the GNU General Public License as published by
+//  the Free Software Foundation, either version 3 of the License, or
+//  (at your option) any later version.
+//
+//  ResInsight is distributed in the hope that it will be useful, but WITHOUT ANY
+//  WARRANTY; without even the implied warranty of MERCHANTABILITY or
+//  FITNESS FOR A PARTICULAR PURPOSE.
+//
+//  See the GNU General Public License at <http://www.gnu.org/licenses/gpl.html>
+//  for more details.
+//
+/////////////////////////////////////////////////////////////////////////////////
+
+#pragma once
+
+#include <vector>
+
+//==================================================================================================
+//
+//==================================================================================================
+class RiaInterpolationTools
+{
+public:
+    static double linear( const std::vector<double>& x, const std::vector<double>& y, double value );
+};

ApplicationCode/UnitTests/CMakeLists_files.cmake

@@ -62,6 +62,7 @@ ${CMAKE_CURRENT_LIST_DIR}/RifActiveCellsReader-Test.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RifCsvDataTableFormatter-Test.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaSummaryCurveAnalyzer-Test.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaStdStringTools-Test.cpp
+${CMAKE_CURRENT_LIST_DIR}/RiaInterpolationTools-Test.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RifWellMeasurementReader-Test.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RiaDateStringParser-Test.cpp
 ${CMAKE_CURRENT_LIST_DIR}/RigHexGradientTools-Test.cpp

ApplicationCode/UnitTests/RiaInterpolationTools-Test.cpp

@@ -0,0 +1,79 @@
+#include "gtest/gtest.h"
+
+#include "RiaInterpolationTools.h"
+
+#include <limits>
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+TEST( RiaInterpolationToolsTest, LinearEmptyData )
+{
+    std::vector<double> x;
+    std::vector<double> y;
+
+    double res = RiaInterpolationTools::linear( x, y, 99.9 );
+    EXPECT_EQ( std::numeric_limits<double>::infinity(), res );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+TEST( RiaInterpolationToolsTest, SingleValue )
+{
+    std::vector<double> x = { 1.0 };
+    std::vector<double> y = { 3.0 };
+
+    double res = RiaInterpolationTools::linear( x, y, 2.0 );
+    EXPECT_EQ( std::numeric_limits<double>::infinity(), res );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+TEST( RiaInterpolationToolsTest, ValidInterval )
+{
+    std::vector<double> x = { 0.0, 1.0 };
+    std::vector<double> y = { 0.0, 2.0 };
+
+    double res = RiaInterpolationTools::linear( x, y, 0.5 );
+    EXPECT_DOUBLE_EQ( 1.0, res );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+TEST( RiaInterpolationToolsTest, ValidIntervalLastBin )
+{
+    std::vector<double> x = { 0.0, 1.0, 100.0, 1100.0 };
+    std::vector<double> y = { 0.0, 2.0, 0.0, 2000.0 };
+
+    double res = RiaInterpolationTools::linear( x, y, 600.0 );
+    EXPECT_DOUBLE_EQ( 1000.0, res );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+TEST( RiaInterpolationToolsTest, ValidIntervalValueTooLow )
+{
+    std::vector<double> x = { 0.0, 1.0 };
+    std::vector<double> y = { 0.0, 2.0 };
+
+    // Outside interval on low side
+    double res = RiaInterpolationTools::linear( x, y, -1.0 );
+    EXPECT_DOUBLE_EQ( std::numeric_limits<double>::infinity(), res );
+}
+
+//--------------------------------------------------------------------------------------------------
+///
+//--------------------------------------------------------------------------------------------------
+TEST( RiaInterpolationToolsTest, ValidIntervalValueTooHigh )
+{
+    std::vector<double> x = { 0.0, 1.0 };
+    std::vector<double> y = { 0.0, 2.0 };
+
+    // Outside interval on high side
+    double res = RiaInterpolationTools::linear( x, y, 100.0 );
+    EXPECT_DOUBLE_EQ( std::numeric_limits<double>::infinity(), res );
+}