Shapefiles to input#

Shapefiles were used to create the input data NODES_FILE. In this section, the steps are discussed to process the shapefiles. QGIS was used, but other software could also be suitable.

Data sources#

Two different data sets were used, both from the CBS. This is a Dutch organization that provides data sets on many subjects. Data sets with region data and with postal code data were used.

Loading the data#

  • Create a new QGIS document.

  • Load the geopackage “cbs_pc4_2021_v2.gpkg” and “cbsgebiedsindelingen2021.gpkg”.

  • Add layers “cbs_pc4_2021” and “provincie_gegeneraliseerd” to the map. Layer “provincie_gegeneraliseerd” should be above layer “cbs_pc4_2021” for improved visibility.

Creating a postal code layer of a province#

  • Manually select all postal codes of the province you want to consider (such as Utrecht), by selecting all postal codes of layer “cbs_pc4_2021” of that province. Note that you cannot simply create an intersection with “provincie_gegeneraliseerd” as this is cartographically simplified.

  • Save the selection by right clicking on the “cbs_pc4_2021” layer and selecting “export > save selected features as”. Save it with a clear name, such as “province_pc4_2021.gpkg” with “save only selected features” selected. The new layer is then called “province_pc4_2021”.

Adding centroids#

  • Go to “processing toolbox > vector geometry > centroids”.

  • Use as input layer “province_pc4_2021.gpkg” and press “run”.

  • Rename the resulting layer to “Centroids”.

  • Save the new layer as geopackage by right clicking on the layer and selecting “make permanent”. You can call it “Centroids”, for example.

Adding centroid attributes#

  • Go to “processing toolbox > vector geometry > add geometry attributes” while having the “Centroids” layer selected.

  • Use “Layer CRS” and call the resulting layer “Centroids_geom”.

  • Save the new layer as geopackage by right clicking the layer and selecting “make permanent”. You can call it “Centroids_geom”, for example.

Saving as CSV file#

  • Save the layer “Centroids_geom” as CSV file by right clicking on the layer and selecting “export > save features as”. Select format “Comma Separated Value” [CSV] and the attributes “postcode4”, “aantal inwoners” (number of inhabitants), “xcoord” and “ycoord”. Select the box “add saved file to map”.

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