Swiss Municipal Data Merger Tool: Manual"
In SMMT: The Swiss Municipal Data Merger Tool Maps Municipalities Over Time

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

library(SMMT)

Introduction

In Switzerland, the landscape of municipalities is changing rapidly mainly due to mergers. The Swiss Municipality Merger Tool (SMMT) automatically detects these mutations and maps municipalities of an old state to municipalities of a new state. The aim of this vignette is to illustrate how to use the functionality of the SMMT.

This figure shows the decrease in municipalities over time:

This figure shows the mutations for the decade 2010-2019:

Source: https://www.atlas.bfs.admin.ch/

How To

Setup

1) Download & unpack the Swiss municipality inventory from the Federal Statistical Office website.

path_inventory_xml <- download_municipality_inventory(path = getwd())

2) Import the inventory into the workspace

mutations_object <- import_CH_municipality_inventory(file_path = path_inventory_xml)
mutations        <- mutations_object$mutations

# Alternative: Use a local available version (e.g. Version from January 1st, 2018):
file_path_inventory_xml <- "path/to/eCH0071_180101.xml"
mutations_object <- import_CH_municipality_inventory(file_path = file_path_inventory_xml)
mutations        <- mutations_object$mutations

Get Mapping Table

1) Define the old state and the new state. Example:

old_state <- as.Date("1961-01-01")
new_state <- as.Date("1963-01-01")

2) Get mapping table

mutations <- structure(list(hist_id = c(11227L, 11240L, 13189L),
district_hist_id = c(10025L, 10025L, 10025L),
kanton_abbr = c("AG", "AG", "AG"),
bfs_nr = c(4025L, 4021L, 4021L),
name = c("Daettwil", "Baden", "Baden"),
admission_nr = c(1000L, 1000L, 1004L),
admission_mode = c(20L, 20L, 26L),
admission_date = structure(c(-3653, -3653, -2922), class = c("Date")),
abolition_nr = c(1004L, 1004L, NA),
abolition_mode = c(29L, 26L, NA),
abolition_date = structure(c(-2923, -2923, NA), class = c("Date")),
change_date = structure(c(-2923, -2923, -2922), class = c("Date"))),
row.names = c(NA, -3L), class = c("tbl_df", "tbl", "data.frame"))

mapping_object <- map_old_to_new_state(mutations, old_state, new_state)
mapping_table  <- mapping_object$mapped

Excerpt of mapping table:

|bfs_nr_new | name_new | bfs_nr_old | name_old | |-----|------|-----|-----| |4021 | Baden | 4021 | Baden | |4021 | Baden | 4025 | Daettwil|

If of relevance, use the information about municipalities which could not be mapped (e.g. due to secessions). For example, if you need to exclude these elements from a dataset.

Definitions

Spatial reference (German: Raumbezug): Set of municipalities at a given point in time. For example, the spatial reference of the Federal Population census year 2000 is the 5 December 2000.

Further information

Details about the Swiss Municipality inventory (German: Historisiertes Gemeindeverzeichnis) at the Federal Statistical Office : https://www.bfs.admin.ch/bfs/de/home/grundlagen/agvch/historisiertes-gemeindeverzeichnis.html
Details about the defined standard: https://www.ech.ch/de/standards/60121