added a missing values method to datetimeColumn.It returns a booleanColumn  Should be added to all columns.
package tech.tablesaw.columns.datetimes;
import com.google.common.base.Strings;
+import tech.tablesaw.api.BooleanColumn;
import tech.tablesaw.api.DateColumn;
import tech.tablesaw.api.DateTimeColumn;
import tech.tablesaw.api.IntColumn;
@@ -375,6 +376,18 @@ public interface DateTimeMapFunctions extends Column<LocalDateTime> {
return newColumn;
}
+ default BooleanColumn missingValues() {
+ BooleanColumn newColumn = BooleanColumn.create(this.name() + " missing?");
+ for (int r = 0; r < this.size(); r++) {
+ if (isMissing(r)) {
+ newColumn.append(BooleanColumn.BYTE_TRUE);
+ } else {
+ newColumn.append(BooleanColumn.BYTE_FALSE);
+ }
+ }
+ return newColumn;
+ }
+
default StringColumn dayOfWeek() {
StringColumn newColumn = StringColumn.create(this.name() + " day of week", this.size());
for (int r = 0; r < this.size(); r++) {
