Added a new package with an Algorithm that takes a txt file and conve…

.checkstyle

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+
+<fileset-config file-format-version="1.2.0" simple-config="true" sync-formatter="false">
+  <fileset name="all" enabled="true" check-config-name="Google Checks" local="false">
+    <file-match-pattern match-pattern="." include-pattern="true"/>
+  </fileset>
+</fileset-config>

src/main/java/com/github/pedrovgs/binarytree/BinaryNode.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package com.github.pedrovgs.binarytree;
 
 /**
@@ -63,14 +64,24 @@ public boolean hasRight() {
   }
 
   @Override public boolean equals(Object o) {
-    if (this == o) return true;
-    if (!(o instanceof BinaryNode)) return false;
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof BinaryNode)) {
+      return false;
+    }
 
     BinaryNode that = (BinaryNode) o;
 
-    if (!data.equals(that.data)) return false;
-    if (left != null ? !left.equals(that.left) : that.left != null) return false;
-    if (right != null ? !right.equals(that.right) : that.right != null) return false;
+    if (!data.equals(that.data)) {
+      return false;
+    }
+    if (left != null ? !left.equals(that.left) : that.left != null) {
+      return false;
+    }
+    if (right != null ? !right.equals(that.right) : that.right != null) {
+      return false;
+    }
 
     return true;
   }

src/main/java/com/github/pedrovgs/equations/Grade2Equation.java

@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2014 Pedro Vicente Gómez Sánchez.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.github.pedrovgs.equations;
+
+/**
+ * This class contains an algorithm that solves 2nd grade equations.
+ * @author ShoeMaker
+ *
+ */
+
+public class Grade2Equation {
+
+  /**
+   * Method solves 2nd grade equations.
+   * @param a from a*x^2
+   * @param b from b*x
+   * @param c the fixed number
+   * @return An array with the solution/solutions of the equation.
+   * @throws IllegalArgumentException there is no Real solution to the equation.
+   */
+  public Double[] solve(double a, double b, double c) {
+
+    double d = (b * b) - (4 * a * c);
+    if (d < 0) {
+      throw new IllegalArgumentException("There is no Real solution to this equation.");
+    }
+    Double[] x = new Double[2];
+    x[0] = (-b + Math.sqrt(d)) / (2 * a);
+    x[1] = (-b - Math.sqrt(d)) / (2 * a);
+    return x;
+  }
+}

src/main/java/com/github/pedrovgs/files/TxtToList.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2014 Pedro Vicente Gómez Sánchez.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.github.pedrovgs.files;
+
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+
+
+/**
+ * This class contains an algorithm that reads txt files and turns them to Lists for further use.
+ * @author ShoeMaker
+ *
+ */
+
+public class TxtToList {
+
+  /**
+   * Method gets a txt file's path. It opens the file and reads it,
+   * then tries to get the txt lines and return them as a List.
+   * @param filepath  The file's path.
+   * @return A List with the file's lines.
+   * @throws IllegalArgumentException when an IOException occurs or the file is empty.
+   */
+  public List<String> readFileToList(String filepath) {
+
+    List<String> datas = new ArrayList<String>();
+    BufferedReader br = null;
+    String line = null;
+    try {
+      br = new BufferedReader(new FileReader(filepath));
+      line = br.readLine();
+      while (line != null) {
+        datas.add(line);
+        line = br.readLine();
+      }
+      br.close();
+    } catch (IOException e) {
+      throw new IllegalArgumentException("Something went wrong. Wrong path or file doesn't exist.");
+    }
+    if (datas.size() == 0) {
+      throw new IllegalArgumentException("File was empty.");
+    }
+    return datas;
+  }
+}

src/main/java/com/github/pedrovgs/linkedlist/ListNode.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package com.github.pedrovgs.linkedlist;
 
 /**
@@ -50,12 +51,18 @@ public void setNext(ListNode<T> next) {
   }
 
   @Override public boolean equals(Object o) {
-    if (this == o) return true;
-    if (!(o instanceof ListNode)) return false;
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof ListNode)) {
+      return false;
+    }
 
     ListNode listNode = (ListNode) o;
 
-    if (!data.equals(listNode.data)) return false;
+    if (!data.equals(listNode.data)) {
+      return false;
+    }
 
     return true;
   }

src/main/java/com/github/pedrovgs/pair/Pair.java

@@ -13,6 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package com.github.pedrovgs.pair;
 
 /**
@@ -31,13 +32,21 @@ public Pair(A a, B b) {
   }
 
   @Override public boolean equals(Object o) {
-    if (this == o) return true;
-    if (!(o instanceof Pair)) return false;
+    if (this == o) {
+      return true;
+    }
+    if (!(o instanceof Pair)) {
+      return false;
+    }
 
     Pair pair = (Pair) o;
 
-    if (!a.equals(pair.a)) return false;
-    if (!b.equals(pair.b)) return false;
+    if (!a.equals(pair.a)) {
+      return false;
+    }
+    if (!b.equals(pair.b)) {
+      return false;
+    }
 
     return true;
   }

src/main/java/com/github/pedrovgs/statistics/Sample.java

@@ -0,0 +1,142 @@
+/*
+ * Copyright (C) 2014 Pedro Vicente Gómez Sánchez.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.github.pedrovgs.statistics;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+
+
+
+public class Sample {
+
+  private List<Object> sample;
+
+  public Sample(List<Object> sample) {
+    this.sample = sample;
+  }
+
+  /**
+   * Method calculates the frequencies of the Sample.
+   * @return A Map of the frequencies of every object in the sample.
+   * @throws IllegalArgumentException when the sample is empty.
+   */
+  public Map<Object, Double> frequencies() {
+
+    if (sample.size() == 0) {
+      throw new IllegalArgumentException("Sample is empty !");
+    }
+
+    Map<Object, Double> freq = new HashMap<Object, Double>();
+    double count;
+    for (int i = 0; i < sample.size(); i++) {
+
+      count = freq.containsKey(sample.get(i)) ? freq.get(sample.get(i)) : 0.0;
+      freq.put(sample.get(i), count + 1);
+
+    }
+    return freq;
+  }
+
+  /**
+   * Method calculates the avg of the Sample.
+   * @return The avg.
+   * @throws IllegalArgumentException when sample is empty or when the Sample is not quantitative.
+   */
+  public double avg() {
+
+    if (sample.size() == 0) {
+      throw new IllegalArgumentException("Sample is empty !");
+    }
+
+    double avg = 0;
+    try {
+      for (int i = 0; i < sample.size(); i++) {
+        avg += Double.parseDouble(sample.get(i).toString());
+      }
+    } catch (Exception e) {
+      throw new IllegalArgumentException("The sample is not quantitative.");
+    }
+    return avg / sample.size();
+  }
+
+  /**
+   * Method calculates the median of the Sample.
+   * @return The median.
+   * @throws IllegalArgumentException when sample is empty or when the Sample is not quantitative.
+   */
+  public double median() {
+
+    if (sample.size() == 0) {
+      throw new IllegalArgumentException("Sample is empty !");
+    }
+
+    double median;
+    double x;
+    double y;
+    try {
+      if (sample.size() % 2 == 0) {
+        x = Double.parseDouble(sample.get(sample.size() / 2 - 1).toString());
+        y = Double.parseDouble(sample.get(sample.size() / 2).toString());
+        median = (x + y) / 2;
+      } else {
+        median = Double.parseDouble(sample.get(sample.size() / 2).toString());
+      }
+    } catch (Exception e) {
+      throw new IllegalArgumentException("The sample is not quantitative.");
+    }
+
+    return median;
+  }
+
+  /**
+   * Method calculates the variance of the Sample.
+   * @return The variance.
+   * @throws IllegalArgumentException when sample is empty or when the Sample is not quantitative.
+   */
+  public double variance() {
+
+    if (sample.size() == 0) {
+      throw new IllegalArgumentException("Sample is empty !");
+    }
+
+    double var = 0;
+    try {
+      for (int i = 0; i < sample.size(); i++) {
+        var += Math.pow((Double.parseDouble(sample.get(i).toString())) - avg(), 2);
+      }
+    } catch (Exception e) {
+      throw new IllegalArgumentException("The sample is not quantitative.");
+    }
+    return var = var / (sample.size() - 1);
+  }
+
+  /**
+   * Method calculates the standardDeviation of the Sample.
+   * @return The standardDeviation.
+   * @throws IllegalArgumentException when sample is empty or when the Sample is not quantitative.
+   */
+  public double standardDeviation() {
+
+    if (sample.size() == 0) {
+      throw new IllegalArgumentException("Sample is empty !");
+    }
+
+    return Math.pow(variance(), 1.0 / 2.0);
+  }
+}