From 7e36e8b071cea6302e8c0b469d33421bc0fad5af Mon Sep 17 00:00:00 2001
From: Rsl1122 <djrapitops@hotmail.com>
Date: Sun, 7 Jul 2019 13:58:41 +0300
Subject: [PATCH] Thought of new Activity index formula

See plot: https://www.wolframalpha.com/input/?i=plot+y+%3D+5+-+5+*+(1+%2F+(pi%2F2+*+x%2B1))+and+y+%3D1+and+y+%3D+2+and+y+%3D+3+and+y+%3D+3.75+from+-0.5+to+3
---
 .../analysis/ActivityIndexQueries.java        | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)
 create mode 100644 Plan/common/src/main/java/com/djrapitops/plan/db/access/queries/analysis/ActivityIndexQueries.java

diff --git a/Plan/common/src/main/java/com/djrapitops/plan/db/access/queries/analysis/ActivityIndexQueries.java b/Plan/common/src/main/java/com/djrapitops/plan/db/access/queries/analysis/ActivityIndexQueries.java
new file mode 100644
index 000000000..afb9270b9
--- /dev/null
+++ b/Plan/common/src/main/java/com/djrapitops/plan/db/access/queries/analysis/ActivityIndexQueries.java
@@ -0,0 +1,52 @@
+/*
+ *  This file is part of Player Analytics (Plan).
+ *
+ *  Plan is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License v3 as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  Plan is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with Plan. If not, see <https://www.gnu.org/licenses/>.
+ */
+package com.djrapitops.plan.db.access.queries.analysis;
+
+/**
+ * Queries for Activity Index that attempts to gain insight into player activity levels.
+ * <p>
+ * Old formula for activity index was not linear and difficult to turn into a query due to conditional multipliers.
+ * Thus a new formula was written.
+ * <p>
+ * {@code T} - Time played after someone is considered active on a particular week
+ * {@code t1, t2, t3} - Time played that week
+ * <p>
+ * Activity index takes into account last 3 weeks.
+ * <p>
+ * Activity for a single week is calculated using {@code A(t) = (1 / (pi/2 * (t/T) + 1))}.
+ * A(t) is based on function f(x) = 1 / (x + 1), which has property f(0) = 1, decreasing from there, but not in a straight line.
+ * You can see the function plotted here https://www.wolframalpha.com/input/?i=1+%2F+(x%2B1)+from+-1+to+2
+ * <p>
+ * To fine tune the curve pi/2 is used since it felt like a good curve.
+ * <p>
+ * Activity index A is calculated by using the formula:
+ * {@code A = 5 - 5 * [A(t1) + A(t2) + A(t3)] / 3}
+ * <p>
+ * Plot for A and limits
+ * https://www.wolframalpha.com/input/?i=plot+y+%3D+5+-+5+*+(1+%2F+(pi%2F2+*+x%2B1))+and+y+%3D1+and+y+%3D+2+and+y+%3D+3+and+y+%3D+3.75+from+-0.5+to+3
+ * <p>
+ * New Limits for A would thus be
+ * {@code < 1: Inactive}
+ * {@code > 1: Irregular}
+ * {@code > 2: Regular}
+ * {@code > 3: Active}
+ * {@code > 3.75: Very Active}
+ *
+ * @author Rsl1122
+ */
+public class ActivityIndexQueries {
+}
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