lookup

Interface

Lookup

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/computing/array/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)

Source Code

Source code is available when you agree to a GP Licence or buy a Commercial Licence.

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