Tutorial: Accumulative Mean Center (Manual Method)

Q: How has the mean center of Starbucks stores in Gangnam, Seoul changed over the years?

Before you begin this tutorial, do the following first:

• Add Starbucks Layer
• Add a Basemap

The method presented in this practice relies on basic QGIS functionality but can be time-consuming for practical use. This practice is designed primarily for learning QGIS operations. For practical cumulative mean center calculation, use the plug-in method

Checking the Layer Attribute Table

With the sbucks layer selected in the Layers panel, press the F6 shortcut key.

Result: The attribute table for sbucks opens. We will use the open_year field to compute cumulative mean centers.

A. Cumulative Mean Center up to 2002

Selecting all stores opened by 2002

[1] From the top menu, click Select Features by Expression…

[2] In Select by Expression, expand Fields and Values and double-click open_year (the editor shows "open_year").

[3] Enter "open_year" <= 2002 and click Select Features to select all stores opened by 2002.

[4] Result: Two stores opened by 2002 are selected (highlighted in yellow).

Adding the cumulative mean center up to 2002

[1] Select sbucks.shp → Vector → Analysis Tools → Mean Coordinates…

[2] Ensure the input layer is sbucks [EPSG:5179].

[3] Check Selected features only and click Run.

[4] Result:

B. Cumulative Mean Center after 2003

Repeat the above steps year by year. For 2003, use "open_year" <= 2003 to select features, then compute the mean center on the selection. Repeat for each year.

Final Result: Cumulative mean centers are created for each year. (Labeling each year will be covered later)