w_data: Construct a spatial weights matrix using observations in a...

In loganstundal/spatialhelpers: Convenience functions for working with spatial data

Description

w_data constructs spatial weights using dyadic data recorded in a data frame. These weights may be symmetric or asymmetric depending on user preference.

Usage

w_data(
  data,
  id1,
  id2,
  flow1,
  flow2,
  flow,
  missing_list = FALSE,
  quitetly = FALSE
)

Arguments

data	A data frame containing dyadic flows
id1	Variable identifying unit 1
id2	Variable identifying unit 2
flow1	Flows into unit 1 from unit 2
flow2	Flows into unit 2 from unit 1
flow	Total flows between dyads. This will override flow1 and flow2 if supplied and return a symmetric matrix
missing_list	For instances where the data contains dyads with no reported flows, the returned weights matrix will contain NAs. Setting this argument to TRUE returns a list of these observations
quitetly	Suppress warning messages

Value

A matrix consisting of weights derived from data

Examples

data(trade)
head(trade)
# Construct a symmetric dyadic matrix
w_symmetric <- w_data(data = trade, id1 = importer1, id2 = importer2,
                      flow = total_trade)

# Recode missing values to 0 if these correspond to cases with no flows:
w_symmetric[is.na(w_symmetric)] <- 0

# Verify symmetry:
isSymmetric(w_symmetric)
w_symmetric["Canada", "Mexico"]
w_symmetric["Mexico", "Canada"]

# Return list of dyads with no flows to explore whether these are missing data
w_missing <- w_data(data = trade, id1 = importer1, id2 = importer2,
                    flow = total_trade, missing_list = TRUE)

w_missing$France # Dyads not reporting trade with France


# Construct an asymmetric dyadic matrix
head(trade)
w_asymmetric <- w_data(data  = trade, id1 = importer1, id2 = importer2,
                       flow1 = flow1, flow2 = flow2)

# Verify asymmetric
isSymmetric(w_asymmetric)

w_asymmetric["Canada", "Mexico"] # Imports of Canada from Mexico in current US millions $
w_asymmetric["Mexico", "Canada"] # Imports of Mexico from Canada in current US millions $

loganstundal/spatialhelpers documentation built on Dec. 21, 2021, 11:46 a.m.