firstflows: Flow Selection from Origins

In flows: Flow Selection and Analysis

Description

Flow selection from origins.

Usage

firstflows(mat, method = "nfirst", ties.method = "first", k)

Arguments

mat	A square matrix of flows.
method	A method of flow selection, one of "nfirst", "xfirst" or "xsumfirst": nfirst selects the k first flows from origins, xfirst selects flows greater than k, xsumfirst selects as many flows as necessary for each origin so that their sum is at least equal to k. If k is not reached for one origin, all its flows are selected.
ties.method	In case of equality with "nfirst" method, use "random" or "first" (see rank).
k	Selection threshold.

Details

As the output is a boolean matrix, use element-wise multiplication to get flows intensity.

Value

A boolean matrix of selected flows.

See Also

firstflowsg, domflows

Examples

# Import data
data(nav)
myflows <- prepflows(mat = nav, i = "i", j = "j", fij = "fij")

# Remove the matrix diagonal
diag(myflows) <- 0

# Select the 2 first flows of each origin
flowSel <- firstflows(mat = myflows, method = "nfirst", ties.method = "first",
                      k = 2)
statmat(mat = myflows * flowSel, output = "none")

# Select flows greater than 2000
flowSel <- firstflows(mat = myflows, method = "xfirst", k = 2000)
statmat(mat = myflows * flowSel, output = "none")

# Select as many flows as necessary for each origin so that their sum is at
# least equal to 20000
flowSel <- firstflows(myflows, method = "xsumfirst", k = 20000)
statmat(mat = myflows * flowSel, output = "none")

# Select each flows that represent at least 10% of the outputs
myflowspct <- myflows / rowSums(myflows) * 100
flowSel <- firstflows(mat = myflowspct, method = "xfirst", k = 10)
statmat(mat = myflows * flowSel, output = "none")

flows documentation built on May 2, 2019, 7:25 a.m.