add DecimalFormat function

virtdata-lib-basics/src/main/java/io/nosqlbench/virtdata/library/basics/shared/formatting/DecimalFormat.java

@@ -0,0 +1,24 @@
+package io.nosqlbench.virtdata.library.basics.shared.formatting;
+
+import io.nosqlbench.virtdata.annotations.Example;
+import io.nosqlbench.virtdata.annotations.ThreadSafeMapper;
+
+import java.util.function.DoubleFunction;
+
+/**
+ * Formats a floating point value to a string using the java.text.DecimalFormat
+ */
+@ThreadSafeMapper
+public class DecimalFormat implements DoubleFunction<String> {
+    private final java.text.DecimalFormat format;
+
+    @Example({"DecimalFormat('.##')","converts a double value to a string with only two digits after the decimal"})
+    public DecimalFormat(String format) {
+        this.format = new java.text.DecimalFormat(format);
+    }
+
+    @Override
+    public String apply(double value) {
+        return this.format.format(value);
+    }
+}