Performs a lookup on the first data set, returning the value in the second. Excel: LOOKUP

Contents

Interface Function Documentation Page Comments

Interface

#include <codecogs/array/search/lookup.h>

using namespace Array::Search;

template<...> B

lookup (A value, std::vector<A> lookup, std::vector<B> result, bool sorted=true) Performs a lookup on the first data set, returning the value in the second. Excel: LOOKUP

Function Documentation

This function looks up a value in the given vector. When value is found in the lookup vector, the function returns the corresponding value from the result vector. It is equivalent to the vector form of the Microsoft Excel function LOOKUP. If the parameter sorted is set to true, then this function uses a binary search approach to find the value in lookup. If an exact match cannot be found then it returns the next largest value.

Warning:

The two vectors lookup and result must be of equal length.

Example:

#include <vector>
#include <iostream>
#include <stdio.h>
#include <codecogs/array/search/lookup.h>
 
using namespace std;
 
int main()
{
  vector<double> rowA;
  vector<char> rowB;
 
  rowA.push_back(-2.3);
  rowA.push_back(1.37);
  rowA.push_back(1.54);
  rowA.push_back(2.02);
  rowA.push_back(2.17);
 
  rowB.push_back('a');
  rowB.push_back('b');
  rowB.push_back('c');
  rowB.push_back('d');
  rowB.push_back('e');
 
  cout<<"lookup vector:\n";
  for (unsigned int i=0; i<rowA.size(); i++) cout<<rowA[i]<<"\t";
  cout<<"\n";
 
  cout<<"result vector:\n";
  for (unsigned int i=0; i<rowB.size(); i++) cout<<rowB[i]<<"\t";
  cout<<"\n";
 
  cout<<"lookup 1.37=";
  cout<<Array::Search::lookup<double, char>(1.37, rowA, rowB);
  cout<<"\n";
 
  cout<<"lookup 1.36=";
  cout<<Array::Search::lookup<double, char>(1.36, rowA, rowB);
  cout<<"\n";
 
  cout<<"lookup 1.36 (sort=false)=";
  cout<<Array::Search::lookup<double, char>(1.36, rowA, rowB, false);
  cout<<"\n";
 
  cout<<"lookup 2.01=";
  cout<<Array::Search::lookup<double, char>(2.01, rowA, rowB);
  cout<<"\n";
}

Output:

lookup vector:
-2.3    1.37    1.54    2.02    2.17
result vector:
  a       b       c       d       e
  lookup 1.37=b
  lookup 1.36=a
  lookup 1.36 (sort=false)=?
  lookup 2.01=c

Parameters:

value	the value to search for in lookup
lookup	a vector of values
result	a vector of values
sorted	indicated is the data lookup vector is sorted.

Returns:

the result value from the result vector

Authors:

Will Bateman (Sep 2005)