Support a simpler syntax for comparing percent delta

Signed-off-by: Jimmy Tanagra <[email protected]>
openhab · Dec 4, 2024 · fdf215b · fdf215b
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diff --git a/bundles/org.openhab.transform.basicprofiles/README.md b/bundles/org.openhab.transform.basicprofiles/README.md
@@ -213,7 +213,12 @@ The `LHS_OPERAND` and the `RHS_OPERAND` can be either one of these:
 - A number with a unit to represent a `QuantityType`, for example `1.2 kW`, or `24 °C`.
 - One of the special functions supported by State Filter:
   - `$DELTA` to represent the absolute difference between the incoming value and the previously accepted value.
+    The calculated delta value is absolute, i.e. it is always positive.
+    For example, with an initial data of `10`, a new data of `12` or `8` would both result in a $DELTA of `2`.
   - `$DELTA_PERCENT` to represent the difference in percentage.
+    It is calculated as `($DELTA / current_data) * 100`.
+    Note that this can also be done by omitting the `LHS_OPERAND` and using a number followed with a percent sign `%` as the `RHS_OPERAND`.
+    See the example below.
   - `$AVERAGE`, or `$AVG` to represent the average of the previous unfiltered incoming values.
   - `$STDDEV` to represent the _population_ standard deviation of the previous unfiltered incoming values.
   - `$MEDIAN` to represent the median value of the previous unfiltered incoming values.
@@ -272,6 +277,19 @@ Number:Power PowerUsage {
 }
 ```
 
+Accept new data only if it's 10% higher or 10% lower than the previously accepted data:
+
+```java
+Number:Temperature BoilerTemperature {
+  channel="mybinding:mything:mychannel" [ profile="basic-profiles:state-filter", conditions="$DELTA_PERCENT > 10" ]
+}
+
+// Or more succinctly:
+Number:Temperature BoilerTemperature {
+  channel="mybinding:mything:mychannel" [ profile="basic-profiles:state-filter", conditions="> 10%" ]
+}
+```
+
 The incoming state can be compared against other items:
 
 ```java

diff --git a/...c/main/java/org/openhab/transform/basicprofiles/internal/profiles/StateFilterProfile.java b/...c/main/java/org/openhab/transform/basicprofiles/internal/profiles/StateFilterProfile.java
@@ -300,8 +300,16 @@ class StateCondition {
 
         public StateCondition(String lhs, ComparisonType comparisonType, String rhs) {
             this.comparisonType = comparisonType;
-            this.lhsString = lhs;
-            this.rhsString = rhs;
+
+            if (lhs.isEmpty() && rhs.endsWith("%")) {
+                // Allow comparing percentages without a left hand side,
+                // e.g. `> 50%` -> translate this to `$DELTA_PERCENT > 50`
+                lhsString = "$DELTA_PERCENT";
+                rhsString = rhs.substring(0, rhs.length() - 1).trim();
+            } else {
+                lhsString = lhs;
+                rhsString = rhs;
+            }
             // Convert quoted strings to StringType, and UnDefTypes to UnDefType
             // UnDefType gets special treatment because we don't want `UNDEF` to be parsed as a string
             // Anything else, defer parsing until we're checking the condition

diff --git a/...st/java/org/openhab/transform/basicprofiles/internal/profiles/StateFilterProfileTest.java b/...st/java/org/openhab/transform/basicprofiles/internal/profiles/StateFilterProfileTest.java
@@ -680,6 +680,13 @@ public static Stream<Arguments> testFunctions() {
                 Arguments.of(decimalItem, "$DELTA_PERCENT >= 10", decimals, DecimalType.valueOf("5.5"), true), //
                 Arguments.of(decimalItem, "$DELTA_PERCENT >= 10", decimals, DecimalType.valueOf("6"), true), //
 
+                Arguments.of(decimalItem, ">= 10 %", decimals, DecimalType.valueOf("4.6"), false), //
+                Arguments.of(decimalItem, ">= 10%", decimals, DecimalType.valueOf("4.6"), false), //
+                Arguments.of(decimalItem, ">= 10%", decimals, DecimalType.valueOf("4.5"), true), //
+                Arguments.of(decimalItem, ">= 10%", decimals, DecimalType.valueOf("5.4"), false), //
+                Arguments.of(decimalItem, ">= 10%", decimals, DecimalType.valueOf("5.5"), true), //
+                Arguments.of(decimalItem, ">= 10%", decimals, DecimalType.valueOf("6"), true), //
+
                 // The following will only accept new data if it is within 10% of the previously accepted data.
                 // so the second and subsequent initial data (i.e.: 2, 3, 4, 5) will be rejected.
                 // The new data is compared against the first (1)
@@ -688,6 +695,11 @@ public static Stream<Arguments> testFunctions() {
                 Arguments.of(decimalItem, "$DELTA_PERCENT < 10", decimals, DecimalType.valueOf("0.91"), true), //
                 Arguments.of(decimalItem, "$DELTA_PERCENT < 10", decimals, DecimalType.valueOf("0.89"), false), //
 
+                Arguments.of(decimalItem, "< 10%", decimals, DecimalType.valueOf("1.09"), true), //
+                Arguments.of(decimalItem, "< 10%", decimals, DecimalType.valueOf("1.11"), false), //
+                Arguments.of(decimalItem, "< 10%", decimals, DecimalType.valueOf("0.91"), true), //
+                Arguments.of(decimalItem, "< 10%", decimals, DecimalType.valueOf("0.89"), false), //
+
                 Arguments.of(decimalItem, "1 == $MIN", decimals, DecimalType.valueOf("20"), true), //
                 Arguments.of(decimalItem, "0 < $MIN", decimals, DecimalType.valueOf("20"), true), //
                 Arguments.of(decimalItem, "$MIN > 0", decimals, DecimalType.valueOf("20"), true), //