binary-searching/test/test.js

Better binary searching

"use strict";

var tape = require("tape");
var bounds = require("../search-bounds.js");
var guard = require("guarded-array");

tape("greaterThanEquals", function (t) {
  var lb = bounds.ge;

  function checkArray(arr, values) {
    var garr = guard(arr);
    for (var l = 0; l < arr.length; ++l) {
      for (var h = l; h < arr.length; ++h) {
        for (var i = 0; i < values.length; ++i) {
          for (var j = l; j <= h; ++j) {
            if (arr[j] >= values[i]) {
              break;
            }
          }
          t.equals(
            lb(garr, values[i], l, h),
            j,
            "search in [" + l + "," + h + "]"
          );
        }
      }
    }
  }

  checkArray([0, 1, 1, 1, 2], [-1, 0, 1, 2, 0.5, 1.5, 5]);

  t.equals(lb([0, 2, 5, 6], 0), 0);
  t.equals(lb([0, 2, 5, 6], 1), 1);
  t.equals(lb([0, 2, 5, 6], 2), 1);
  t.equals(lb([0, 2, 5, 6], 3), 2);
  t.equals(lb([0, 2, 5, 6], 4), 2);
  t.equals(lb([0, 2, 5, 6], 5), 2);
  t.equals(lb([0, 2, 5, 6], 6), 3);

  function cmp(a, b) {
    return a - b;
  }

  t.equals(lb([0, 1, 1, 1, 2], -1, cmp), 0);
  t.equals(lb([0, 1, 1, 1, 2], 0, cmp), 0);
  t.equals(lb([0, 1, 1, 1, 2], 1, cmp), 1);
  t.equals(lb([0, 1, 1, 1, 2], 2, cmp), 4);
  t.equals(lb([0, 1, 1, 1, 2], 0.5, cmp), 1);
  t.equals(lb([0, 1, 1, 1, 2], 1.5, cmp), 4);
  t.equals(lb([0, 1, 1, 1, 2], 5, cmp), 5);

  t.equals(lb([0, 2, 5, 6], 0, cmp), 0);
  t.equals(lb([0, 2, 5, 6], 1, cmp), 1);
  t.equals(lb([0, 2, 5, 6], 2, cmp), 1);
  t.equals(lb([0, 2, 5, 6], 3, cmp), 2);
  t.equals(lb([0, 2, 5, 6], 4, cmp), 2);
  t.equals(lb([0, 2, 5, 6], 5, cmp), 2);
  t.equals(lb([0, 2, 5, 6], 6, cmp), 3);

  t.end();
});

tape("lessThan", function (t) {
  var lu = bounds.lt;

  function checkArray(arr, values) {
    var garr = guard(arr);
    for (var l = 0; l < arr.length; ++l) {
      for (var h = l; h < arr.length; ++h) {
        for (var i = 0; i < values.length; ++i) {
          for (var j = h; j >= l; --j) {
            if (values[i] > arr[j]) {
              break;
            }
          }
          t.equals(
            lu(garr, values[i], l, h),
            j,
            i + " - indexOf(" + values[i] + ")=" + j + " [" + l + "," + h + "]"
          );
        }
      }
    }
  }

  checkArray([0, 1, 1, 1, 2], [-1, 0, 1, 2, 0.5, 1.5, 5]);

  t.end();
});

tape("greaterThan", function (t) {
  var lb = bounds.gt;

  function checkArray(arr, values) {
    var garr = guard(arr);
    for (var l = 0; l < arr.length; ++l) {
      for (var h = l; h < arr.length; ++h) {
        for (var i = 0; i < values.length; ++i) {
          for (var j = l; j <= h; ++j) {
            if (arr[j] > values[i]) {
              break;
            }
          }
          t.equals(lb(garr, values[i], l, h), j);
        }
      }
    }
  }

  checkArray([0, 1, 1, 1, 2], [-1, 0, 1, 2, 0.5, 1.5, 5]);

  t.end();
});

tape("lessThanEquals", function (t) {
  var lu = bounds.le;

  function checkArray(arr, values) {
    var garr = guard(arr);
    for (var i = 0; i < values.length; ++i) {
      for (var j = arr.length - 1; j >= 0; --j) {
        if (values[i] >= arr[j]) {
          break;
        }
      }
      t.equals(
        lu(garr, values[i]),
        j,
        i + " - indexOf(" + values[i] + ")=" + j
      );
    }
  }

  checkArray([0, 1, 1, 1, 2], [-1, 0, 1, 2, 0.5, 1.5, 5]);

  t.end();
});

tape("equals", function (t) {
  var lu = bounds.eq;

  function checkArray(arr, values) {
    var garr = guard(arr);
    for (var i = 0; i < values.length; ++i) {
      if (arr.indexOf(values[i]) < 0) {
        t.equals(lu(garr, values[i]), -1);
      } else {
        t.equals(arr[lu(garr, values[i])], values[i]);
      }
    }
  }

  checkArray([0, 1, 1, 1, 2], [-1, 0, 1, 2, 0.5, 1.5, 5]);

  t.end();
});