Merge pull request #2 from Breeding-Insight/bug/BI-2055-1

[BI-2055] - Remove missingValueString tablesaw values

Author: HMS17

core/src/main/java/tech/tablesaw/io/TypeUtils.java

@@ -23,17 +23,12 @@
 public final class TypeUtils {
 
   /** Strings representing missing values in, for example, a CSV file that is being imported */
-  private static final String missingInd1 = "NaN";
-
-  private static final String missingInd2 = "*";
-  private static final String missingInd3 = "NA";
   private static final String missingInd4 = "null";
-  private static final String missingInd5 = "N/A";
 
-  // No default missing indicators
+  // Only null should be default missing indicator for now. null will be removed in BI-2486
   // TODO: Allow this to be configurable?
   public static final ImmutableList<String> MISSING_INDICATORS =
-      ImmutableList.of(missingInd1, missingInd2, missingInd4, missingInd5);
+      ImmutableList.of(missingInd4);
 
   /** Private constructor to prevent instantiation */
   private TypeUtils() {}

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

@@ -528,7 +528,7 @@ void testWithMissingValue2() throws IOException {
 
     Table t = Table.read().csv("../data/missing_values2.csv");
     assertEquals(1, t.stringColumn(0).countMissing());
-    assertEquals(1, t.numberColumn(1).countMissing());
+    assertEquals(0, t.numberColumn(1).countMissing());
     assertEquals(0, t.numberColumn(2).countMissing());
   }