How Icon Map Slicer works

Every Icon Map Slicer map is built from three parts: a basemap, data layers that draw the rows of your report, and reference layers that add context. Selecting items on the map filters the rest of the report page. Once you know how a row of data finds its layer, and what a selection filters, the rest of the visual falls into place.

The three parts of a map

From version 1.1.0.11 you can also use ArcGIS content: ArcGIS basemaps and web maps, ArcGIS reference layers, and an ArcGIS layer joined to your data. Maps added in 1.1.0.11 or later can also offer readers a choice of basemaps from several sources.

Data layers respond to the report. They follow slicers and filters, show tooltips, and are what you select to filter the page. Reference layers do not change with your data.

Layers are drawn from the bottom up, and each layer has a position in that order. You can change it, for example to draw a boundary file above your circles or place names above everything.

Fields: how data reaches the map

You give Icon Map Slicer data by adding fields to its field wells in the Build pane, as with any Power BI visual. The field wells are:

The Fields reference describes each one in full.

One row is one thing on the map

Power BI groups your data by the field in * ID (required) and sends Icon Map Slicer one row for each ID value. Each row becomes one item on the map. Three consequences follow:

• The ID must be unique for each thing you want to draw. If two stores share an ID, they become one row and one circle.
• Without an ID, Power BI sends no rows and nothing can be drawn.
• When you select an item, the report is filtered to its ID value. Choose an ID field that the other visuals on the page can be filtered by.

Because the other field wells hold summarized values, set Longitude (X) and Latitude (Y) to Average (select the arrow next to the field in the Build pane). With a unique ID, the average of one row is the row's own value.

By default Power BI sends up to 30,000 rows. You can raise this. See Data rows and limits.

A row picks its layer by the fields it fills in

There is no setting that says "draw this row as a circle". Instead, each row is drawn by the layer whose fields it fills in, as long as it leaves the fields that belong to other layers empty.

In the example:

• Store A has a longitude, a latitude and a circle size, and nothing else. It is a circle.
• Route B has an origin and a destination. It is a line.
• Region C has only a feature reference. It is joined to a shape in a file.
• Row D fills in the fields of a circle and also a feature reference. Circles skip it, because a feature reference marks a row as a shape. Shapes (from files) skip it, because it has coordinates. It is not drawn.

Three rules cover most cases:

1. Fill in what the layer needs. A circle needs * ID (required), Longitude (X), Latitude (Y) and Circle Size. A line needs the two destination fields instead of a size. Choose a layer type lists the fields for every layer.
2. Leave the other layers' fields empty on that row. Empty means the field is not in the visual, or the row's value is blank. A blank text cell counts as empty, the same as a BLANK() returned by a measure.
3. Turn the layer on. A row is only drawn if its layer is switched on. On a new map, Circles is on and the other data layers are off.

This is also how one map shows several layer types at once: keep the rows in one table and fill in different fields on different rows. Combine several layers in one map explains the patterns.

Selecting on the map filters the report

This is what makes Icon Map Slicer a slicer. When a reader selects items on the map, the visual applies a filter on the * ID (required) field to the report page, in the same way as a Power BI slicer.

• Other visuals filter. Every visual on the page that can be filtered by the ID field shows only the selected items. Power BI applies the filter through the relationships in your model, so the ID field's table must relate to the data in the other visuals.
• The map does not filter itself. It keeps every item, shows the selected ones solid and fades the rest.
• The filter is saved with the report. It stays in place when you save the report, and bookmarks capture it.
• Clearing. Click the selected items again, or click an empty part of the map (unless you turn off Background Click Clears Selection), to remove the filter.

You can select in several ways:

Other visuals filter the map in the usual way: a slicer, a filter or a selection in another visual reduces the rows that Icon Map Slicer receives, and the map draws only those. Icon Map Slicer does not cross-highlight, and is not highlighted by other visuals.

See How Icon Map Slicer filters for the details.

Where the settings are

You can set up a map in three places. They write the same settings, so you can move between them freely.

A good way to work is to add and arrange layers in the Layer Manager, then go to the Format pane when you want a value to follow your data or to set up selection.

Values from your data: conditional formatting

Many settings have an fx button in the Format pane. Use it to take the value from a field or measure, or from a rule or color scale, so that each row gets its own color, size, label text or visibility. This is how you color circles by a measure or show a different icon for each category. See Conditional formatting.

How a report reader uses the map

Readers can pan, zoom, tilt and rotate the map, hover for tooltips, and select items to filter the rest of the report page. You decide which selection tools and controls appear on the map. See How Icon Map Slicer filters and Map controls.

Related

• Build your first map
• Choose a layer type
• Combine several layers in one map
• How Icon Map Slicer filters