Video - Exploring the Attribute Table and Layer Properties Box of Vector Data

Catalogue number: Catalogue number: 89200005

Issue number: 2020005

Release date: February 17, 2020

QGIS Demo 5

Exploring the Attribute Table and Layer Properties Box of Vector Data - Video transcript

(The Statistics Canada symbol and Canada wordmark appear on screen with the title: "Demo 5 - Exploring the Attribute Table and Layer Properties Box of Vector Data")

Following up from interacting with datasets in the Map Canvas, today we'll explore additional information and parameters found in the Attribute Table and Layer Properties Box. The Attribute Table contains additional variables for analyzing and visualizing vector data, while the Layer Properties box contains tabs that summarize information and provide additional functions. We'll quickly summarize some of the key tabs, their content and use, which we'll cover in detail in later demos.

So to open the Attribute Table of a layer, we can left-click it in the Layers panel and select the Attribute table icon, or right-click the layer and select Open Attribute Table.

Within the table, each column reports an additional variable tied to the dataset. These are referred to as fields in GIS, whereas each row corresponds to a specific feature or geometry in the canvas.

Using the tabs on the left-side we can select features. With an individual feature selected, we can right-click and Zoom to the Feature, and if we still couldn't see it we can also flash the feature. In this case our feature was hidden by the Census Subdivision layer.

Like the Interactive Selection tools, we can use Shift and Control keys to select multiple features. Shift to select features within a range and Ctrl to add individual features. In conjunction, we can can select features both within and between ranges. We could also then zoom to our selection. As shown, when features are selected in the Attribute Table they are also highlighted in the Canvas and vice-versa - in yellow in the Canvas and Blue in the Attribute Table.

To sort a field, ascending or descending we can left-click once or twice on the field name. This could help select features by specific criteria of interest such as selecting all features within a particular province. We can zoom to the selection again and Invert our Selection, to switch the selected features.

To move selected features to the top of the attribute table, click the Move Selection to Top icon. So now if we add any additional features to the selection they are by default moved to the top of the table. We could also copy their information and paste it into an external spreadsheet editor for further analysis.

We could apply a field filter, expanding Show All Features and specifying the field to filter by and specific criteria to use in filtering the table. Subsequently, the only remaining entries are those that satisfy the filter criteria, in this case the Province Name being Manitoba.

If we want a dynamic representation of attribute features based on the current scale and extent, we can use Show Only Selected Features Visible on Map. Now if we change the scale or location our table is filtered accordingly.

To enable additional tools we can enable the editor. This enables us to add or delete features, or add and delete fields. We can click on an individual cell to edit its information, or for a selection of features use the Update Field Bar, specifying the field to update and the new attributes to update to – in this case clicking Update Selected. If we wanted to retain these changes we would save them, but in this case – since we want to keep our attribute table uniform - we'll discard the changes and clear our selection.

To open the Layer Properties box of a layer we can right-click it and select Properties or simply double-left click it in the Layers Panel.

The Layer Properties box contains various tabs which both summarize information and provide additional functions.

The Information tab summarizes the spatial characteristics as well as some of the attribute information within a dataset.   

In the Source Tab we can rename a layer as we did with the Census Subdivision. We can also use the Query Builder to filter features. This would filter the geometries of the layer in the Canvas as opposed to the table when using the Field Filter earlier.

The following four tabs are for visualization. We'll explore the Symbology and Labels tab in an upcoming demo, where we can apply different symbology styles to visualize fields within the attribute table, as well as differing labelling schemes. We can create Diagrams with the attribute information and, when enabled apply 3D visualizations.

The Source Fields tab provides more information on the Field Names, Types and additional parameters within the Attribute table. With editor enabled we can add or delete a field, as well as rename a field.

Within the Joins tab we can link datasets together – used for one-to-one joins - by a field with common entries. So for example, we could join the Census Subdivision layer using the unique Census Division identifier to link the datasets together. To remove the join, simply click it and select the minus icon.

The final tab I'd like to discuss is apply a scale-dependent visibility in the Rendering tab – where we can define the scale at which a dataset should begin or suspend rendering. We can set it either from the drop-downs or set it to the current map canvas scale by clicking on this icon. This is helpful for large or highly detailed datasets that take a long-time to render. Now if we hit OK and zoom in – our dataset remains visible, but if we zoom out beyond the specified scale rendering is suspended.

Congratulations everyone! Today you've learned key skills in exploring, selecting and filtering features within the attribute table, performing simple edits and the use of some tabs within the Layer Properties box. In the next demo, we'll cover procedures for creating vector datasets, which includes delineating features and populating their attributes.

(Canada wordmark appears.)

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