Author: tdunning
Date: Fri Apr 22 06:13:36 2011
New Revision: 1095871
URL: http://svn.apache.org/viewvc?rev=1095871&view=rev
Log:
MAHOUT-672 - the forgotten files
Added:
mahout/trunk/utils/src/main/java/org/apache/mahout/utils/Bump125.java
mahout/trunk/utils/src/test/java/org/apache/mahout/utils/Bump125Test.java
Added: mahout/trunk/utils/src/main/java/org/apache/mahout/utils/Bump125.java
URL:
http://svn.apache.org/viewvc/mahout/trunk/utils/src/main/java/org/apache/mahout/utils/Bump125.java?rev=1095871&view=auto
==============================================================================
--- mahout/trunk/utils/src/main/java/org/apache/mahout/utils/Bump125.java
(added)
+++ mahout/trunk/utils/src/main/java/org/apache/mahout/utils/Bump125.java Fri
Apr 22 06:13:36 2011
@@ -0,0 +1,45 @@
+package org.apache.mahout.utils;
+
+/**
+ * Helps with making nice intervals at arbitrary scale.
+ *
+ * One use case is where we are producing progress or error messages every
time an incoming
+ * record is received. It is generally bad form to produce a message for
<i>every</i> input
+ * so it would be better to produce a message for each of the first 10
records, then every
+ * other record up to 20 and then every 5 records up to 50 and then every 10
records up to 100,
+ * more or less. The pattern can now repeat scaled up by 100. The total
number of messages will scale
+ * with the log of the number of input lines which is much more survivable
than direct output
+ * and because early records all get messages, we get indications early.
+ */
+public class Bump125 {
+ private static final int[] bumps = {1, 2, 5};
+
+ static int scale(double value, double base) {
+ double scale = value / base;
+ // scan for correct step
+ int i = 0;
+ while (i < bumps.length - 1 && bumps[i + 1] <= scale) {
+ i++;
+ }
+ return bumps[i];
+ }
+
+ static long base(double value) {
+ return Math.max(1, (long) Math.pow(10, (int)
Math.floor(Math.log10(value))));
+ }
+
+ private long counter = 0;
+
+ public long increment() {
+ long delta;
+ if (counter >= 10) {
+ final long base = base(counter / 4.0);
+ int scale = scale(counter / 4.0, base);
+ delta = (long) (base * scale);
+ } else {
+ delta = 1;
+ }
+ counter += delta;
+ return counter;
+ }
+}
Added: mahout/trunk/utils/src/test/java/org/apache/mahout/utils/Bump125Test.java
URL:
http://svn.apache.org/viewvc/mahout/trunk/utils/src/test/java/org/apache/mahout/utils/Bump125Test.java?rev=1095871&view=auto
==============================================================================
--- mahout/trunk/utils/src/test/java/org/apache/mahout/utils/Bump125Test.java
(added)
+++ mahout/trunk/utils/src/test/java/org/apache/mahout/utils/Bump125Test.java
Fri Apr 22 06:13:36 2011
@@ -0,0 +1,23 @@
+package org.apache.mahout.utils;
+
+import com.google.common.collect.Lists;
+import org.junit.Test;
+
+import java.util.Iterator;
+
+public class Bump125Test extends MahoutTestCase {
+ @Test
+ public void testIncrement() throws Exception {
+ Iterator<Integer> ref = Lists.newArrayList(1, 2, 3, 4, 5, 6, 7,
+ 8, 9, 10, 12, 14, 16, 18, 20, 25, 30, 35, 40, 50, 60,
+ 70, 80, 100, 120, 140, 160, 180, 200, 250, 300, 350,
+ 400, 500, 600, 700, 800, 1000, 1200, 1400, 1600, 1800,
+ 2000, 2500, 3000, 3500, 4000, 5000, 6000, 7000)
+ .iterator();
+ Bump125 b = new Bump125();
+ for (int i = 0; i < 50; i++) {
+ final long x = b.increment();
+ assertEquals(ref.next().longValue(), x);
+ }
+ }
+}
