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Definition of filters in the main map display



Filters are used in DELFT-FEWS to define the locations that are displayed on the main map display, and that can be selected to display data. Filters are defined to arrange locations, with associated parameters in logical groups. Each filter is defined as a collection of time series sets.

Filters may be defined as a nested structure, allowing for the definition of a hierarchical set of filters.

When available on the file system, the name of the XML file is for example: Filters 1.00 default.xml

Figure 31 Elements of the filters configuration

The main elements of the filters configuration are shown in the image above and explained further below:

  • description: Optional description of the filter configuration. Used for reference purposes only.
  • defaultFilterId: Filter that is selected automatically on start up of FEWS. If not defined no filter will be selected.
  • timeSeriesSets: Optional element that may appear an unlimited amount of times. It is possible to explicitly define every (child)filter. This may result in to many repeating timeSeriesSet definitions. Therefore it is also possible (since version 2009.02) to define groups of timeSeriesSets that can be used many times in the filter, additionally by using constraints on the location attributes (see timeSeriesSetId & constraints). Each <timeSeriesSets> element should contain an id attribute and one or more <timeSeriesSet> elements. 
  • filter: Required element with the definition of a filter. Multiple entries may exist where multiple filters are defined.


Definition of a filter. Multiple entries may exist where multiple filters are defined. Each filter may contain either a set of one or more time series set, or a child filter. The child is a reference to another filter definition that again contains either a child filter or a list of time series sets. This structure is used to construct a hierarchal tree view of filters.


  • id: Id of the filter. Used when this filter is referenced elsewhere in the configuration. Used in the tree view in the main display when no name attribute is given.
  • name: optional name for the filter. When given it is used in the tree view in the main display.

The possible elements are each explained in their own section.


Optional description of the filter configuration. Used for reference purposes only.

validationIconsViewPeriod and validationIconsVisible

Both elements are optional, only one of them may be configured for a filter. 

The validation icons are only visible when ALL the selected filters, including there children, have the validation period or validation icons visible configured.

  • validationIconsViewPeriod: Since 2017.01, optional element. Calculate validation icons in the specified period. By using this you can for example ignore the validation problems for the most recent data.
  • validationIconsVisible: Optional element allowing the user to make use of the additional validation icons available in the explorer (2009.01). When set to true, all validation icons in the view period of the time series sets will be shown.


Optional element available since 2013.01.

In versions 2013.01 until 2017.01, when this filter is selected the last value for the selected parameter is visible in the location label on the map. If several filters are selected, the last value is only shown if all filters have this element set to true. When a parent filter is selected, the last values are only shown if the element is set to true for all child filters and the parent filter. 

Since 2017.02 a button was added to the explorer which controls whether the labels show the last value. When a filter selection is made for which in previous versions the last values would be shown, the button is now turned on automatically instead. Note that this means the user can still turn of the last values by turning the button back off (clicking it). Also note that when a different selection is made (while the button is still on), the button will remain turned on even if <lastValueVisible> is not set to true for the new selection. 

Note that in all versions, the last values are only shown for locations which do not have a custom label configured. Additionally, the values are only shown when a single parameter is selected in the data viewer. Finally, only values in the time span (relativeViewPeriod) configured for the timeSeriesSet will be found.


Optional element, available since 2019.01, which shows the threshold icons based on the last non-missing value within the relative view period specified.


Optional element, when this filter is selected the map will automatically zoom to the specified map extent. 


Optional element, set a permission to control who can view this filter.


Optional element, set a permission to control who can edit timeseries enumerated in this filter (only editable timeseries can be editted).


Reference to another filter. The child element refers to the ID of the other filter as a foreign key.


  • foreignKey: Reference to ID of another filter, that is displayed as child filter


Definition of a time series set belonging to a filter. Multiple time series sets may be defined.

The time span defined in the time series sets in the filter has an important function. It determines the time span checked for determining status icons (e.g. missing data) in the main map display.

Not all locations need to be included in a filter. Locations that are not defined, will never be visible to the user.

The readWrite parameter defined in the time series set included in the filter will determine if the time series may be edited by the user. If this parameter is set to read only then the time series will not support editing. This is the case for external time series only. Simulated time series are read only by convention. Notice that editable timeSeriesSets should have synchLevel 5 to get the edits saved into the central database.

<!--Example (time series sets not expanded) -->
	<filter id="Config Example">
		<child foreignKey="Nested Filter"/>
	<filter id="Nested Filter">
	<filter id="Main Level Filter">

Figure32 Example of filter configuration, as defined in the example XML configuration above.

timeSeriesSetId & constraints

Instead of an extensive definition of all possible time series that usually will be repeated for different types of locations and various districts, it is possible to define the timeSeriesSets once and to use it various times through all filters. At this point you refer to such a timeSeriesSets and optionally add some constraints on the location attributes. Notice that location attributes only can be defined in the locationSets for locations that are read from an ArcGIS shape DBF file. See the example below.

It is possible to define filters that may become empty: no locations comply with the constraints. These filters are not displayed. An advantage of this approach is that all possible filters can be defined once and automatically become visible when a location complies to the constraints.


parameter attribute

Since 2016.01 filters can be automatically generated based on different parameter attribute values. 

	<filter id="groupByParameterAttribute">
		<relativeViewPeriod start="-100000" end="0" unit="day"/>
			<idStartsWith prefix=""/>

This will work for multivalued attributes as well

			<attribute id="ATTRIBUTE_1">
			<attribute id="ATTRIBUTE_2">

In parameterAttributes.csv below multivalued attributes are defined for some parameters like "BESDWG_%" which has values "E1a" & "E1b" for "ATTRIBUTE_1".

For parameter "BEMSRTJT_m" the attribute "ATTRIBUTE_1" has values "D1" & "E1b".


When  "ATTRIBUTE_1" is used to generate filters based on its values the next filters are generated: A1, B1a, B1b, E1a, E1b, D1.

When selecting filter "E1a" only parameter "Beschaduwing" will appear because that is the only one with "E1a" as value for "ATTRIBUTE_1"


When selecting filter "E1b" both parameters "Beschaduwing_%" & "Bemonsteringstraject_m" will appear because they both have "E1b" in their multivalued "ATTRIBUTE_1":

Group by location and qualifier attributes

Since 2020.01 it is also possible to atomatically generate filters based on location and qualifier attributes.

Nested GroupBy 

GroupBy filters can be nested as well and mutliple parameter, location and qualifier attributes can be used in any order and there is no limit on how many attributes to specify. However, creating too many of separate subfilters can result in a drastically degraded performance. Note that grouping by parameter attributes is available since 2016.01 while grouping by location atttributes is available from version 2020.01.

The config example below will first create subfilters based on parameters which all have the same parameter attribute values.

The parameter filters will have subfilters based on location attributes and those subfilters will in turn have their own subfilters based on qualifier attribute values. 

<filter id="GroupByNested" name="GroupByNested">
   <relativeViewPeriod start="-31" end="0" unit="day"/>

Additional time series

Additional time series can be configured in filters. These series are found via attribute functions (in the <locationFunctionEquals selected=@ATTRIBUTE_ID_A@ additional="@ATTRIBUTE_ID_B@"> element) of the selected time series and the additional time series. When the attribute functions evaluate to the same value the additional time series are added as invisible by default. When additional time series are available the icon of the visibility dialog will change which shows that invisible time series are available and can be made visible.

When it is desired that the additional time series are added only for the same locations then all locations should have an attribute that is equal to their id for example LOC_ID and the locationFunctionEqualselement can be used as follows: 

<locationFunctionEquals selected=@LOC_ID@ additional="@LOC_ID@">

In the example below  locationFunctionEquals selected="@LOC_ID@" additional="@PEILGEBIED_ATT @"/> is used which will show all a timeseries from the additional time series set where the location has an attribute value PEILGEBIED_ATT which equals the LOC_ID attribute of the shown location of the normal time series set, which can be multiple or even 0.

When the attribute functions evaluate to the same value the additional time series are added as invisible by default. When additional time series are available the icon of the visibility dialog will change which shows that invisible time series are available and can be made visible. Each additional time series element can be given a name, this name will be used as prefix in the legend of the time series and as GroupNode label in the visibility dialog.

	<filter id="GEBGEM_OPVL_PLGB_BEMALINGSGEBIED_DE_KEULEVAART" name="Peilbesluit bemalingsgebied De Keulevaart">
			<attributeTextEquals id="PEILBESLUIT" equals="bemalingsgebied De Keulevaart"/>
		<additionalTimeSeries name="*O*">
			<locationFunctionEquals selected="@LOC_ID@" additional="@PEILGEBIED_ATT@"/>
				<timeSeriesType>external historical</timeSeriesType>
				<timeStep unit="nonequidistant"/>
				<relativeViewPeriod unit="day" start="-40" end="0"
					startOverrulable="false" endOverrulable="false"/>
				<readWriteMode>editing visible to all future task runs</readWriteMode>
		<additionalTimeSeries name="**O**">
			<locationFunctionEquals selected="@LOC_ID@" additional="@PEILGEBIED_ATT@"/>
				<timeSeriesType>external historical</timeSeriesType>
				<timeStep unit="day" timeZone="GMT+1"/>
				<relativeViewPeriod unit="day" start="-40" end="0"/>
				<readWriteMode>read only</readWriteMode>



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