The Attribute Table

Attribute table and selections!!

Joins

Field Calculator

Edit Attribute Table too…. here… otherwise do more indept in the afternoon and just introduce as part of layer properties here,…

https://ubc-library-rc.github.io/gis-thematic-mapping/content/hands-on1.html

The Attribute Table

The Attribute Table is where you can view the tabular data associated with vector datasets. Here, you can query your data by running complex selections, directly edit individual features, and perform mathematical operations on your layers. See the QGIS documentation on working with the attribute table for more.

To open a layer’s attribute table, right-click the layer in the Layers Panel and go to “Open Attribute Table”.

ALSO TOOLBAR TOOL

Exploring the Attribute Table

To Do

Open the attribute table of the X layer. Note that there are several attributes (columns) that describe each feature (row) in this dataset. Manually re-size the column widths until you can read each attribute.

The column headings are called Attributes. Each column is called a Field and each row is called a Feature. Each feature corresponds to one point on your map. (If you were looking at the attribute table of vanHoods, each feature would correspond to a polygon, and so on.) At the top of the Attribute Table you can see there are 3,224 features, or trees, in this dataset. Each feature, or tree, has 10 attributes, including the common_name and height_m. Notice that text values are left-justified whereas numerical values are right-justified. Sometimes cell values will be NULL meaning the feature contains no information for a given value. For instance, very few trees have information for the data planted.

Notice that text values are left-justified whereas numerical values are right-justified. Sometimes QGIS will read numbers as text, disabling mathematical operations. If this happens, you will have to create a new field and set the type to either integer or decimal.

You can order Features in descending or ascending order by clicking on the attribute.

• Click height_m to sort all Features from shortest to tallest. Click height_m again to sort from tallest to shortest. (Notice some of the shortest trees were planted just last month.)
• Click common_name to sort the trees in alphabetical order.

sort by occupation

Selecting by Attribute

Selections are different than using the Identify tool to highlight a feature and expose its attributes. Selections select a set of features in the Attribute Table. Once attributes are thus selected, you can edit them, export them, or perform more analysis.

There are many ways to make selections in QGIS.

• You may manually select features from the map canvas using the Selection Toolbar ;
• You may select features by location using the Select by location vector analysis tool;
• And you can select features by attribute within the Attribute Table.

Other selections - we’ll explore more in the afternoon. right now - select bakers from xyz.

or pick occupation

run selections for bakers from all 3 demographic layers, then from businesses to find bakeries???

To run a select by attribute…

Select bakers from x

we will use same skill to select religion? later on… and map by census tracts. or population density by ward or sensus tracts.