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Widen 'em up!

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git-svn-id: https://samskivert.googlecode.com/svn/trunk@2280 6335cc39-0255-0410-8fd6-9bcaacd3b74c
This commit is contained in:
mdb
2008-03-21 21:33:39 +00:00
parent 277454fe78
commit cdc5941479
1 changed files with 54 additions and 63 deletions
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src/java/com/samskivert/util/RandomUtil.java
+54 -63
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@@ -28,9 +28,8 @@ import java.util.Random;
import com.samskivert.Log;
/**
* Provides miscellaneous utility routines to simplify obtaining useful random
* number values and to centralize seeding and proper care and feeding of the
* pseudo-random number generator.
* Provides miscellaneous utility routines to simplify obtaining useful random number values and to
* centralize seeding and proper care and feeding of the pseudo-random number generator.
*/
public class RandomUtil
{
@@ -38,8 +37,8 @@ public class RandomUtil
public static final Random rand = new Random();
/**
* Returns a pseudorandom, uniformly distributed <code>int</code>
* value between 0 (inclusive) and the specified value (exclusive).
* Returns a pseudorandom, uniformly distributed <code>int</code> value between 0 (inclusive)
* and the specified value (exclusive).
*
* @param high the high value limiting the random number sought.
*/
@@ -49,21 +48,20 @@ public class RandomUtil
}
/**
* Returns a pseudorandom, uniformly distributed <code>int</code>
* value between <code>high</code> and <code>low</code>, exclusive of each.
* Returns a pseudorandom, uniformly distributed <code>int</code> value between
* <code>high</code> and <code>low</code>, exclusive of each.
*/
public static int getInt (int high, int low)
{
if (high - low - 1 <= 0) {
throw new IllegalArgumentException(
"Invalid range [high=" + high + ", low=" + low + "]");
throw new IllegalArgumentException("Invalid range [high=" + high + ", low=" + low + "]");
}
return low + 1 + rand.nextInt(high - low - 1);
}
/**
* Returns a pseudorandom, uniformly distributed float value between
* 0.0 (inclusive) and the specified value (exclusive).
* Returns a pseudorandom, uniformly distributed float value between 0.0 (inclusive) and the
* specified value (exclusive).
*
* @param high the high value limiting the random number sought.
*/
@@ -73,26 +71,26 @@ public class RandomUtil
}
/**
* Returns a pseudorandom, uniformly distributed float value between
* 0.0 (inclusive) and the specified value (exclusive).
* Returns a pseudorandom, uniformly distributed float value between 0.0 (inclusive) and the
* specified value (exclusive).
*
* @param high the high value limiting the random number sought.
* @param r the random number generator to use
*/
public static float getFloat (float high, Random r)
{
return r.nextFloat() * high;
}
return r.nextFloat() * high;
}
/**
* Pick a random index from the array, weighted by the value of the
* corresponding array element.
* Pick a random index from the array, weighted by the value of the corresponding array
* element.
*
* @param weights an array of non-negative integers.
* @return an index into the array, or -1 if the sum of the weights
* is less than 1.
*
* For example, passing in {1, 0, 3, 4} will return
* @return an index into the array, or -1 if the sum of the weights is less than 1. For
* example, passing in {1, 0, 3, 4} will return:
*
* <table><tr><td>0</td><td>1/8th of the time</td></tr>
* <tr><td>1</td><td>never</td></tr>
* <tr><td>2</td><td>3/8th of the time</td></tr>
@@ -111,21 +109,20 @@ public class RandomUtil
return ii;
}
}
// Impossible!
Log.logStackTrace(new Throwable());
Log.logStackTrace(new Throwable()); // Impossible!
return 0;
}
/**
* Pick a random index from the array, weighted by the value of the
* corresponding array element.
* Pick a random index from the array, weighted by the value of the corresponding array
* element.
*
* @param weights an array of non-negative floats.
* @return an index into the array, or -1 if the sum of the weights
* is less than or equal to 0.0 or any individual element is negative.
*
* For example, passing in {0.2, 0.0, 0.6, 0.8} will return
* @return an index into the array, or -1 if the sum of the weights is less than or equal to
* 0.0 or any individual element is negative. For example, passing in {0.2, 0.0, 0.6, 0.8}
* will return:
*
* <table><tr><td>0</td><td>1/8th of the time</td></tr>
* <tr><td>1</td><td>never</td></tr>
* <tr><td>2</td><td>3/8th of the time</td></tr>
@@ -137,14 +134,15 @@ public class RandomUtil
}
/**
* Pick a random index from the array, weighted by the value of the
* corresponding array element.
* Pick a random index from the array, weighted by the value of the corresponding array
* element.
*
* @param weights an array of non-negative floats.
* @return an index into the array, or -1 if the sum of the weights
* is less than or equal to 0.0 or any individual element is negative.
*
* For example, passing in {0.2, 0.0, 0.6, 0.8} will return
* @return an index into the array, or -1 if the sum of the weights is less than or equal to
* 0.0 or any individual element is negative. For example, passing in {0.2, 0.0, 0.6, 0.8}
* will return:
*
* <table><tr><td>0</td><td>1/8th of the time</td></tr>
* <tr><td>1</td><td>never</td></tr>
* <tr><td>2</td><td>3/8th of the time</td></tr>
@@ -171,17 +169,15 @@ public class RandomUtil
}
}
// Impossible!
Log.logStackTrace(new Throwable());
Log.logStackTrace(new Throwable()); // Impossible!
return 0;
}
/**
* Picks a random object from the supplied array of values. Even
* weight is given to all elements of the array.
* Picks a random object from the supplied array of values. Even weight is given to all
* elements of the array.
*
* @return a randomly selected item or null if the array is null or of
* length zero.
* @return a randomly selected item or null if the array is null or of length zero.
*/
public static <T> T pickRandom (T[] values)
{
@@ -190,15 +186,13 @@ public class RandomUtil
}
/**
* Picks a random object from the supplied array of values, not
* including the specified skip object as a possible selection
* (equality with the skipped object is referential rather than via
* {@link Object#equals}). The element to be skipped must exist in the
* array exactly once. Even weight is given to all elements of the
* array except the skipped element.
* Picks a random object from the supplied array of values, not including the specified skip
* object as a possible selection (equality with the skipped object is referential rather than
* via {@link Object#equals}). The element to be skipped must exist in the array exactly
* once. Even weight is given to all elements of the array except the skipped element.
*
* @return a randomly selected item or null if the array is null, of
* length zero or contains only the skip item.
* @return a randomly selected item or null if the array is null, of length zero or contains
* only the skip item.
*/
public static <T> T pickRandom (T[] values, T skip)
{
@@ -238,9 +232,8 @@ public class RandomUtil
}
/**
* Picks a random object from the supplied List. The specified skip
* object will be skipped when selecting a random value. The skipped
* object must exist exactly once in the List.
* Picks a random object from the supplied List. The specified skip object will be skipped when
* selecting a random value. The skipped object must exist exactly once in the List.
*
* @return a randomly selected item.
*/
@@ -250,9 +243,8 @@ public class RandomUtil
}
/**
* Picks a random object from the supplied List. The specified skip
* object will be skipped when selecting a random value. The skipped
* object must exist exactly once in the List.
* Picks a random object from the supplied List. The specified skip object will be skipped when
* selecting a random value. The skipped object must exist exactly once in the List.
*
* @return a randomly selected item.
*/
@@ -275,13 +267,13 @@ public class RandomUtil
}
/**
* Picks a random object from the supplied iterator (which must
* iterate over exactly <code>count</code> objects.
* Picks a random object from the supplied iterator (which must iterate over exactly
* <code>count</code> objects.
*
* @return a randomly selected item.
*
* @exception NoSuchElementException thrown if the iterator provides
* fewer than <code>count</code> elements.
* @exception NoSuchElementException thrown if the iterator provides fewer than
* <code>count</code> elements.
*/
public static <T> T pickRandom (Iterator<T> iter, int count)
{
@@ -298,16 +290,15 @@ public class RandomUtil
}
/**
* Picks a random object from the supplied iterator (which must
* iterate over exactly <code>count</code> objects. The specified skip
* object will be skipped when selecting a random value. The skipped
* object must exist exactly once in the set of objects returned by
* Picks a random object from the supplied iterator (which must iterate over exactly
* <code>count</code> objects. The specified skip object will be skipped when selecting a
* random value. The skipped object must exist exactly once in the set of objects returned by
* the iterator.
*
* @return a randomly selected item.
*
* @exception NoSuchElementException thrown if the iterator provides
* fewer than <code>count</code> elements.
* @exception NoSuchElementException thrown if the iterator provides fewer than
* <code>count</code> elements.
*/
public static <T> T pickRandom (Iterator<T> iter, int count, T skip)
{