When you import data collected with Maptionnaire to ArcGIS, you may have to do some initial clean-up and selection of the data. This article details some of the ways in which you can use ArcGIS's Selection tools to do that.
- Clean the dataset
Sometimes respondents may have misunderstood a question or skipped it, resulting in missing values, mistyped attributes or irrelevant entries in the response data. Using functions like Select by Attributes or Select by Location is a good way to clean the dataset.
- Focus on specific attributes
Using selections allows you to focus on specific issues. For example, you may want to display only those respondents who answered a particular question, reported a specific condition, or belong to a certain demographic group.
Let's say a planning team wants to analyze how 18–25-year-olds view public transportation: Use Select by Attributes to select only the responses where Age = 18–25 and compare them with other groups.
- Compare locations
When using location-based selection, you can easily filter responses that fall within a specific area (e.g city boundary) or lie near a specific feature (e.g. development area). This makes it possible to compare responses across different locations or understand how people’s experiences vary depending on their surroundings.
For example: a city wants to understand how residents from different districts perceive safety at night: Use district boundaries to select responses inside each district and analyze them separately.
- Use a set of selected features to select another
Imagine you have city boundary polygons and point data representing residents' responses. You can first select the city polygon(s) you want to focus on, and then use that selection to select the resident response points that fall within those cities.
In GIS software there are multiple ways to select specific features. The easiest way is to select manually, but it is only recommended if you just need a few features from a layer.
For complex selections it’s recommended to use:
- Select by Location: this means that the users can select features from a layer, based on their location relative to features of another layer.
- Select by Attributes: this means that the users can select features based on their attributes in the Attribute table. The users can write an expression to select certain features on the map.
The following example was made in ArcGIS Pro.
The Select by Attributes function can be opened from multiple locations in ArcGIS Pro. You can find it directly on the Map ribbon but also on the top menu of the attribute table window.
In this example we are selecting points, where the respondent's age is greater than 18.
For the Input Rows parameter, we are selecting a point layer with respondent's data.
Set the Selection type to New selection.
Next to the “Where” clause we selected the Age field, because this field contains the age of respondents and set the value to 18.
After setting all parameters, click OK. The selected points will be highlighted on the map.
If you want to clear the selection, click on the Clear button on the Map ribbon.
The Select by Location tool is available on the Map ribbon.
In the next example we are going to select points that fall within the city of Helsinki's polygon:
As Input Features we are selecting the layer that contains the point data.
As the Relationship parameter we are selecting Intersect.
Under Selecting Features, select the layer that contains the Helsinki polygon.
The Selection Type should be New selection.
Then click OK.
In the Relationship setting, there are many options to choose from. If you are not sure which one to use, read the tool tip, which has a short description about all of them.
If you want to clear the selection, click on the Clear button on the Map ribbon.
Often the selected set of data needs to be exported for further analytics. When a selection is active on a layer in ArcGIS Pro, you can export the selected features directly from the layer's context menu. In the layer list, right click the point layer while the selection is still active, then choose Data > Export Features.
In the Export Features window, as the Output Feature Class parameter, set the name for the new file. Make sure that the Use the selected records option is active and click OK.
The exported file will be automatically added as a layer to the map.