WORKING WITH LAYERS
Layer Visibility
The Contents Pane also controls layer visibility. You can toggle the layer visibility using the checkbox next to each layer in the Contents Pane.
- Use the visibility checkbox next to the househldPopMotherTong_joinToThis layer to turn on and off the visibility of the layer and any other layers in the map.
Feature Layer Tab
Almost everything you might want to do with a layer can be done under the Feature Layer tabs. There are often short-cuts to do these tasks also, but the Feature Layer tab can help you first find ways to work with layers.
(Note: Almost every sub-command can be found 2 ways; as an icon on the feature tab, or by right-click and ‘properties’ options in the contents.)
The data we’ll be working with represents Household Population by Mother Tongue from the 2016 Census. It was retrieved from SimplyAnalytics, one of the databases available from the UBC library. A mother tongue language is a person’s first language. We will use data on household population by mother tongue language aggregated by census tract.
In this workshop, we will analyze this data to understand the spatial distribution of linguistic diversity in Vancouver. Although another Census variable, language spoken at home, could also be used, for the purposes of our analysis, we’ll use household population by mother tongue to visualize where languages are spoken across the city.
1 Click on the househldPopMotherTong_joinToThis layer. The Feature Layer set (orange) appears at the top of the screen. There are 3 tabs under the Feature Layer set: Appearance, Labeling, and Data.
2 Go to the Data tab. The first block has a Definition Query Tool. The second block has a Table Tool with a button to open the ‘Attribute Table’. Click on this to open the attribute table.
You can also open the attribute table of a layer by right-clicking on that layer in the Contents panel and selecting Attribute Table to open it.
3 Scroll all the way to right of the attribute table and notice the fieldnames and data present.
Do you see any replication? What do you think the numbers represent?
Every feature you see in a map has a backend database associated with it where information is stored, called the attribute table, which appears much like a spreadsheet. The most basic method of analysis in GIS is selection and sub-setting of data by attribute values.
This dataset had to be downloaded as multiple datasets and joined together. All but one remaining dataset have already been joined together for you.
4 Right-Click on the househldPopMotherTong_joinTbl layer and select Attribute Table to open it.
Do you recognize any fieldnames from the attribute table of the first layer we opened?
Reflection Question
(Click the text for the answer)
What do you think **VALUE0, VALUE1**, etc. represent?
These represent different languages.
Notice there is another layer listed under Standalone Tables called variable_names.
5 Right-Click on the variable_names layer and select Open.
Notice there is no way to view variable_names on the map. It only exists as a table. Each data download for the language data came with both a spatial feature layer and an accompanying table. The information in the table was used to rename the VALUE fields in the spatial feature layer with language names. When bringing Census data into a GIS, it often requires additional manipulation before it can be used or understood.
6 Expand the width of Field1 to view all of the information.
You’ll notice that these values represent four additional languages which are not yet present in the househldPopMotherTong_joinToThis layer.
In the next section, we’ll rename the VALUE fields in the househldPopMotherTong_joinTbl layer and then join this to the househldPopMotherTong_joinToThis layer.