====TravelWriter (Analytic Filter)====

===Description===
The **TravelWriter** filter is used to write values when items are in a certain point in your process or physical location.

It's primarily used to create [[heatmap|heatmaps]] when one axis of your heatmap is an element that moves or changes state over time.

The filter changes your data significantly, from a pair of values to an array.

Note that the //function// parameter only applies when the //channel// remains steady.

===Parameters===
^Name^Default^Meaning^
|Channel|//<blank>//|The column to use as the moving/state-changing axis|
|Min|0|The minimum element in the array|
|Max|100|The maximum element in the array|
|Function|max|The function (//min// or //max//) that determines which value is stored in each array element|

===Example===
<code>
<filter type="TravelWriter">
     <channel>Position</channel>
     <min>0</min>
     <max>200</max>
     <function>min</function>
</filter>
</code>

//Records the a value as Position changes over a range of 0-200//

==Example Input Sequence==
//Input//
^Index^Value^Position^
|07:00:00|10|5|
|07:00:05|12|4|
|07:00:10|12|5|
|07:00:15|12|6|
|07:00:20|8|6|

**Output**
^Index^1^2^3^4^5^6^...^
|07:00:20|nan|nan|nan|12|12|8|...|