Support percentage by parsing percentage to double (#906)

* support percentage by parsing percentage to double and add corresponding tests

* support percentage by parsing percentage to double and add corresponding tests(update)

* simpify code

* Solve conflict

core/src/main/java/tech/tablesaw/columns/numbers/DoubleParser.java

@@ -1,6 +1,8 @@
 package tech.tablesaw.columns.numbers;
 
 import com.google.common.collect.Lists;
+import java.text.NumberFormat;
+import java.text.ParseException;
 import tech.tablesaw.api.ColumnType;
 import tech.tablesaw.columns.AbstractColumnParser;
 import tech.tablesaw.io.ReadOptions;
@@ -24,9 +26,14 @@ public boolean canParse(String s) {
       return true;
     }
     try {
-      Double.parseDouble(AbstractColumnParser.remove(s, ','));
+      if (isPercent(AbstractColumnParser.remove(s, ','))) {
+        s = AbstractColumnParser.remove(s, ',');
+        Number number = NumberFormat.getPercentInstance().parse(s);
+      } else {
+        Double.parseDouble(AbstractColumnParser.remove(s, ','));
+      }
       return true;
-    } catch (NumberFormatException e) {
+    } catch (NumberFormatException | ParseException e) {
       // it's all part of the plan
       return false;
     }
@@ -42,6 +49,14 @@ public double parseDouble(String s) {
     if (isMissing(s)) {
       return DoubleColumnType.missingValueIndicator();
     }
+    if (isPercent(AbstractColumnParser.remove(s, ','))) {
+      s = AbstractColumnParser.remove(s, ',').substring(0, s.length() - 1);
+      return Double.parseDouble(s) / 100.0;
+    }
     return Double.parseDouble(AbstractColumnParser.remove(s, ','));
   }
+
+  private boolean isPercent(String s) {
+    return s.charAt(s.length() - 1) == '%';
+  }
 }

core/src/test/java/tech/tablesaw/api/DoubleParserTest.java

@@ -0,0 +1,52 @@
+/*
+ * 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 tech.tablesaw.api;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+import tech.tablesaw.columns.numbers.DoubleParser;
+
+class DoubleParserTest {
+  @Test
+  void testCanParse1() {
+    DoubleParser doubleParser = new DoubleParser(ColumnType.DOUBLE);
+    assertTrue(doubleParser.canParse("1.3"));
+  }
+
+  @Test
+  void testCanParse2() {
+    DoubleParser doubleParser = new DoubleParser(ColumnType.DOUBLE);
+    assertTrue(doubleParser.canParse("1.3%"));
+  }
+
+  @Test
+  void testCanParse3() {
+    DoubleParser doubleParser = new DoubleParser(ColumnType.DOUBLE);
+    assertFalse(doubleParser.canParse("%"));
+  }
+
+  @Test
+  void testParseDouble1() {
+    DoubleParser doubleParser = new DoubleParser(ColumnType.DOUBLE);
+    assertEquals(1.3, doubleParser.parseDouble("1.3"));
+  }
+
+  @Test
+  void testParseDouble2() {
+    DoubleParser doubleParser = new DoubleParser(ColumnType.DOUBLE);
+    assertEquals(0.012, doubleParser.parseDouble("1.2%"));
+  }
+}

core/src/test/java/tech/tablesaw/io/csv/CsvReaderTest.java

@@ -49,10 +49,13 @@
 import tech.tablesaw.api.ColumnType;
 import tech.tablesaw.api.DateColumn;
 import tech.tablesaw.api.DateTimeColumn;
+import tech.tablesaw.api.DoubleColumn;
 import tech.tablesaw.api.LongColumn;
 import tech.tablesaw.api.ShortColumn;
 import tech.tablesaw.api.StringColumn;
 import tech.tablesaw.api.Table;
+import tech.tablesaw.columns.numbers.DoubleColumnType;
+import tech.tablesaw.columns.numbers.NumberColumnFormatter;
 import tech.tablesaw.io.AddCellToColumnException;
 
 /** Tests for CSV Reading */
@@ -846,6 +849,26 @@ public void preserveQuote() throws IOException {
     assertEquals(table.get(0, 0), out.get(0, 0));
   }
 
+  @Test
+  public void testReadCsvWithPercentage1() throws IOException {
+    Table table = Table.read().csv(CsvReadOptions.builder("../data/currency_percent.csv"));
+    assertEquals(DoubleColumnType.instance(), table.columnTypes()[1]);
+    assertEquals(DoubleColumnType.instance(), table.columnTypes()[2]);
+  }
+
+  @Test
+  public void testReadCsvWithPercentage2() throws IOException {
+    Table table = Table.read().csv(CsvReadOptions.builder("../data/currency_percent.csv"));
+    DoubleColumn column = (DoubleColumn) table.column(1);
+    assertEquals("0.0132", column.getString(0));
+    assertEquals("0.32768", column.getString(1));
+    assertEquals("1", column.getString(2));
+    column.setPrintFormatter(NumberColumnFormatter.percent(2));
+    assertEquals("1.32%", column.getString(0));
+    assertEquals("32.77%", column.getString(1));
+    assertEquals("100.00%", column.getString(2));
+  }
+
   @Test
   public void testSkipRowsWithInvalidColumnCount() throws IOException {
     Table table =

data/currency_percent.csv

@@ -0,0 +1,4 @@
+Currency,Percentage,double
+$10.3,1.32%,13.14
+$50.10,32.768%,35
+$10,100%,93.131