Differences

This shows you the differences between two versions of the page.

--- transformations:rule [2015/01/29 23:16] – created dmitry
+++ transformations:rule [2019/05/30 06:58] – dmitry
@@ Line 1: / Line 1: @@
 ===== Rule =====
-This transformation calculates new or replaces column by using nested IF...THEN...ELSE conditions. While the same result can be achieved using an expression with nested [[syntax:functions:if]] functions the use of Rule transformation is recommended for clarity and readability.
+This action calculates new or replaces existing column by using one or several ordered IF...THEN...ELSE conditions. The conditions are checked one by one until a satisfying condition is found. When a satisfying condition is found, the result is calculated and all other conditions are ignored. When no satisfying condition is found, the default calculation is applied.
-Rule transformation is somewhat similar to //switch// or //case// statements in popular programming languages.
+The order of conditions is significant as conditions are checked starting from the first (top). Therefore conditions that come first have priority over conditions that come after them.
+While the same result can be achieved using an expression with nested [[syntax:functions:if]] functions, the use of Rule action is recommended for clarity, readability, and the ease of rearranging the order.
+EXAMPLE
+**Source table:** Average income and deductions
+^  Country  ^  Gross income   ^  Disposable income  ^  Compulsory deductions  ^
+| United States  |  56067  |  45582  |  18.7%  |
+| Australia  |  51050  |  42617  |  16.52%  |
+| Switzerland  |  53716  |  48414  |  9.87%  |
+| Canada  |  45896  |  37469  |  18.36%  |
+**Objective:** Add a column describing the average spending potential in each country as low or high, based on the disposable income.
+The spending potential is high if the disposable income is $40,000 or more.
+**Transformation parameters:**
+  * Create new column: Spending
+  * Calculated as: if ([Disposable income] > 40000), then HIGH.
+  * If none of the condition above is met: Default to LOW
+**Output table:**
+^  Country  ^  Gross income   ^  Disposable income  ^  Compulsory deductions  ^  Spending  ^
+| United States  |  56067  |  45582  |  18.7%  |  HIGH  |
+| Australia  |  51050  |  42617  |  16.52%  |  HIGH  |
+| Switzerland  |  53716  |  48414  |  9.87%  |  HIGH  |
+| Canada  |  45896  |  37469  |  18.36%  |  LOW  |
+** See also**
+ * [[https://community.easymorph.com/t/place-stronger-conditions-first-in-the-rule-action/1113|Community: Place stronger conditions first in the Rule action]]