Package 'epiflows'

Title: Predicting Disease Spread from Flow Data
Description: Provides functions and classes designed to handle and visualise epidemiological flows between locations. Also contains a statistical method for predicting disease spread from flow data initially described in Dorigatti et al. (2017) <doi:10.2807/1560-7917.ES.2017.22.28.30572>. This package is part of the RECON (<https://www.repidemicsconsortium.org/>) toolkit for outbreak analysis.
Authors: Pawel Piatkowski [aut, cre] , Paula Moraga [aut] , Isobel Blake [ctb, dtc], Thibaut Jombart [aut], VP Nagraj [aut], Zhian N. Kamvar [aut] , Salla E. Toikkanen [aut]
Maintainer: Pawel Piatkowski <[email protected]>
License: MIT + file LICENSE
Version: 0.2.1
Built: 2024-11-09 04:38:54 UTC
Source: https://github.com/reconhub/epiflows

Help Index

Subset 'epiflows' objects

Description

An epiflows object inherits the epicontacts class, so the subsetting mechanism is also inherited. The benefits is that it's extremely flexible. However, this also means that it's possible for the contacts to contain IDs that are not present in the locations metadata and vice versa. The best way to consistently subset an epiflows object is present in the examples.

Usage

## S3 method for class 'epiflows'
x[i, j, k = TRUE, l = TRUE, ...]

Arguments

x

An epiflows object.
i

An integer, logical, or character vector of one or more location.
j

An integer, logical, or character vector to subset the flows data frame.
k

A character vector of one or more columns to be retained in the location data.
l

A character vector of one or more columns to be retained in the flows data frame. Note: if using numbers, the first column stands for the first column after "n".
...

Additional parameters passed to [.epicontacts.

Details

Returns a subset of an epiflows object.

Value

An epiflows object.

Author(s)

Zhian N. Kamvar

Examples

data(Brazil_epiflows)
# You can subset, but the flows information will still be present
Brazil_epiflows[j = "Espirito Santo"]
# To help with this, use `thin` from epiflows
epicontacts::thin(Brazil_epiflows[j = "Espirito Santo"])
epicontacts::thin(Brazil_epiflows[j = c("Espirito Santo", "Rio de Jenerio")])

Add/Retrieve location coordinates

Description

Adds/Retrieves longitude/latitude values to location data within an epiflows object. Coordinates are added to object's locations slot as lon and lat columns.

Usage

add_coordinates(
  x,
  coordinates = c("lon", "lat"),
  loc_column = "id",
  overwrite = FALSE
)

get_coordinates(x, ...)

## S3 method for class 'epiflows'
get_coordinates(x, location = NULL, ...)

Arguments

x

An epiflows object.
coordinates

Either names of the appended columns with longitudes and latitudes, respectively (default: "lon" and "lat") or a data frame with longitude and latitude columns.
loc_column

Name of the column where location names are stored (default: "country").
overwrite

If TRUE, retrieves all geocodes, even those already retrieved. If FALSE (default), overwrites only NAs.
...

unused
location

a character specifying a single location to return as a vector of coordinates. You cannot specify multiple locations with this parameter. Defaults to 'NULL', indicating all locations.

Value

An updated epiflows object.

Author(s)

Pawel Piatkowski, Salla Toikkanen, Zhian Kamvar

See Also

map_epiflows(); plot.epiflows(); get_locations(); get_vars(); global_vars()

Examples

# Setting up the data
data("Brazil_epiflows")
data("YF_coordinates")
get_coordinates(Brazil_epiflows) # no coordinates yet
ef <- add_coordinates(Brazil_epiflows, YF_coordinates[-1])
get_coordinates(ef)
get_coordinates(ef, location = "Espirito Santo") # coordinates for Espirito Santo
if (interactive()) {
  # You can use google maps' geocode functionality if you have a decent 
  # internet connection
  # NOTE: you may need to authenticate with Google Maps API beforehand
  # using ggmap::register_google()
  ef2 <- add_coordinates(Brazil_epiflows, loc_column = "id")
  ef2
}

Convert to SpatialLinesDataFrame class

Description

Convert to SpatialLinesDataFrame class

Usage

as.SpatialLinesDataFrame(x)

## S3 method for class 'epiflows'
as.SpatialLinesDataFrame(x)

Arguments

x

an epiflows object

Value

an object of class [sp::SpatialLinesDataFrame]

Examples

data("Brazil_epiflows")
data("YF_coordinates")
ef <- add_coordinates(Brazil_epiflows, YF_coordinates[-1])
ef2 <- epicontacts::thin(ef[j = c("Espirito Santo", "Italy"), contacts = "both"])
as.SpatialLinesDataFrame(ef2)

epiflows

Description

epiflows is a package for predicting and visualising spread of infectious diseases based on flows between geographical locations, e.g., countries. epiflows provides functions for calculating spread estimates, handling flow data, and visualization.

Details

The main functions of the package are make_epiflows() for constructing an epiflows object and estimate_risk_spread() to estimate potential spread. Visualization is available for maps, networks, and grids.

For details, see the vignettes:
vignette("introduction", package = "epiflows")
vignette("epiflows-class", package = "epiflows")

Travel-related disease cases spreaded to other locations from an infectious location

Description

Calculates the mean and 95% confidence interval of the estimated number of disease cases that could potentially seed a disease outbreak in the locations they are travelling to, comprising exportations (infected residents of the infectious location travelling abroad during the incubation or infectious period), and importations (international tourists infected by the disease during their stay in the infectious location and returning to their home location). The mean and 95% confidence intervals are obtained by numerically sampling n_sim times from the incubation and infectious period distributions. If parameter return_all_simulations is set to TRUE, the function returns all simulations for each location.

Usage

estimate_risk_spread(...)

## Default S3 method:
estimate_risk_spread(
  location_code = character(0),
  location_population = numeric(0),
  num_cases_time_window = numeric(0),
  first_date_cases = character(0),
  last_date_cases = character(0),
  num_travellers_to_other_locations = numeric(0),
  num_travellers_from_other_locations = numeric(0),
  avg_length_stay_days = numeric(0),
  r_incubation = function(n) {
 },
  r_infectious = function(n) {
 },
  n_sim = 1000,
  return_all_simulations = FALSE,
  ...
)

## S3 method for class 'epiflows'
estimate_risk_spread(
  x,
  location_code = character(0),
  r_incubation = function(n) {
 },
  r_infectious = function(n) {
 },
  n_sim = 1000,
  return_all_simulations = FALSE,
  ...
)

Arguments

...

Arguments passed onto the default method.
location_code

a character string denoting the infectious location code
location_population

population of the infectious location
num_cases_time_window

cumulative number of cases in infectious location in time window
first_date_cases

string with the date of the first disease case in infectious location ("YYYY-MM-DD")
last_date_cases

string with the date of the last disease case in infectious location ("YYYY-MM-DD")
num_travellers_to_other_locations

number of travellers from the infectious location visiting other locations (T_D)
num_travellers_from_other_locations

number of travellers from other locations visiting the infectious location (T_O)
avg_length_stay_days

average length of stay in days of travellers from other locations visiting the infectious location. This can be a common number for all locations or a vector with different numbers for each location
r_incubation

a function with a single argument n generating 'n' random incubation periods
r_infectious

a function with a single argument n generating 'n' random durations of infectious period
n_sim

number of simulations from the incubation and infectious distributions
return_all_simulations

logical value indicating whether the returned object is a data frame with all simulations (return_all_simulations = TRUE) or a data frame with the mean and lower and upper limits of a 95% confidence interval of the number of cases spread to each location (return_all_simulations = FALSE)
x

an epiflows object

Value

if return_all_simulations is TRUE, data frame with all simulations. If return_all_simulations is FALSE, data frame with the mean and lower and upper limits of a 95% confidence interval of the number of cases spread to each location

Author(s)

Paula Moraga, Zhian Kamvar (epiflows class implementation)

References

Dorigatti I, Hamlet A, Aguas R, Cattarino L, Cori A, Donnelly CA, Garske T, Imai N, Ferguson NM. International risk of yellow fever spread from the ongoing outbreak in Brazil, December 2016 to May 2017. Euro Surveill. 2017;22(28):pii=30572. DOI: doi:10.2807/1560-7917.ES.2017.22.28.30572

See Also

Construction of epiflows object: make_epiflows()
Default variables used in the epiflows implementation: global_vars()
Access metadata from the epiflows object: get_vars()

Examples

## Using an epiflows object --------------------------------

data("YF_flows")
data("YF_locations")
ef <- make_epiflows(flows         = YF_flows, 
                    locations     = YF_locations, 
                    pop_size      = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases     = "num_cases_time_window",
                    first_date    = "first_date_cases",
                    last_date     = "last_date_cases"
)
## functions generating incubation and infectious periods
incubation <- function(n) {
  rlnorm(n, 1.46, 0.35)
}

infectious <- function(n) {
  rnorm(n, 4.5, 1.5/1.96)
}

res <- estimate_risk_spread(ef, 
                            location_code          = "Espirito Santo",
                            r_incubation           = incubation,
                            r_infectious           = infectious,
                            n_sim                  = 1e5,
                            return_all_simulations = TRUE)
boxplot(res, las = 3)

## Using other data --------------------------------------------------
data(YF_Brazil)
indstate <- 1 # "Espirito Santo" (indstate = 1), 
              # "Minas Gerais" (indstate = 2), 
              # "Southeast Brazil" (indstate = 5)

res <- estimate_risk_spread(
  location_code = YF_Brazil$states$location_code[indstate], 
  location_population = YF_Brazil$states$location_population[indstate], 
  num_cases_time_window = YF_Brazil$states$num_cases_time_window[indstate], 
  first_date_cases = YF_Brazil$states$first_date_cases[indstate], 
  last_date_cases = YF_Brazil$states$last_date_cases[indstate],
  num_travellers_to_other_locations = YF_Brazil$T_D[indstate,],
  num_travellers_from_other_locations = YF_Brazil$T_O[indstate,],
  avg_length_stay_days = YF_Brazil$length_of_stay,
  r_incubation = incubation,
  r_infectious = infectious,
  n_sim = 100000,
  return_all_simulations = FALSE
)
head(res)

Access flow data

Description

This accessor extract flow data from an epiflows object. get_flows is a generic with a method defined for epiflows objects.

Usage

get_flows(x, ...)

## S3 method for class 'epiflows'
get_flows(x, from = NULL, to = NULL, all = FALSE, ...)

Arguments

x

An 'epiflows' object.
...

unused
from

a character string defining which regions should be included in the flows
to

a character string defining which regions should be included in the flows
all

when 'TRUE', all the columns of the flows data frame will be returned. Defaults to 'FALSE', which returns "from", "to", and "n".

Value

A data.frame with 3 columns:

  • from: origin of the flow

  • to: destination of the flow

  • n: magnitude of the flow—can be a number of passengers per unit of time, a rate, a probability of migration

Author(s)

Zhian N. Kamvar

See Also

get_n(); For location metadata: get_locations(); get_vars(), get_pop_size(), get_coordinates()

Examples

data("Brazil_epiflows")
head(get_flows(Brazil_epiflows))
get_flows(Brazil_epiflows, from = "Minas Gerais")
get_flows(Brazil_epiflows, to = "Minas Gerais")
get_flows(Brazil_epiflows, from = "Italy", to = "Minas Gerais")

Access population identifiers in epiflows objects

Description

this will return the unique population ID for your epiflows object.

Usage

get_id(x, ...)

Arguments

x

an epiflows object
...

arguments passed on to epicontacts::get_id()

Value

a character vector of population IDs

Author(s)

Zhian N. Kamvar

See Also

epicontacts::get_id(); get_vars(); get_pop_size(); global_vars()

Examples

data("Brazil_epiflows")
get_id(Brazil_epiflows)

Access flow data

Description

This accessor extract location data from an epiflows object. get_locations is a generic with a method defined for epiflows objects.

Usage

get_locations(x, ...)

## S3 method for class 'epiflows'
get_locations(x, ...)

Arguments

x

An epiflows object.
...

unused

Value

A data.frame with at least 1 column called id, specifying the id of the location used in the flows data frame.

Author(s)

Thibaut Jombart, Zhian Kamvar

See Also

get_flows(); get_id(); get_pop_size(); get_vars(); get_coordinates(); global_vars()

Examples

data("Brazil_epiflows")
get_locations(Brazil_epiflows)

get the number of cases per flow

Description

This convenience function will return a named vector containing the number of cases flowing to or from a given region.

Usage

get_n(x, from = NULL, to = NULL, ...)

## S3 method for class 'epiflows'
get_n(x, from = NULL, to = NULL, ...)

Arguments

x

an epiflows object
from

a character vector of length one specifying the location from which the flows originate
to

a character vector of length one specifying the location to which the flows terminate
...

unused

Details

There are three possible outputs of this function:

  • no options specified: an un-named vector, equivalent to get_flows(x)$n

  • from = X: a named vector of cases flowing from X

  • to = X: a named vector of cases flowing to X

Value

a character vector

See Also

get_flows(); For location metadata: get_vars(), get_pop_size(), get_coordinates()

Examples

data(Brazil_epiflows)
get_n(Brazil_epiflows, from = "Espirito Santo")
get_n(Brazil_epiflows, to   = "Espirito Santo")

Get population size for each entry in locations

Description

Get population size for each entry in locations

Usage

get_pop_size(x)

## S3 method for class 'epiflows'
get_pop_size(x)

Arguments

x

an epiflows object

Value

a named vector of population sizes

See Also

get_vars(), global_vars()

Examples

data("Brazil_epiflows")
get_pop_size(Brazil_epiflows)

Access location metadata

Description

This accessor extracts variables from the locations data frame in an epiflow object. get_vars is a generic with a method defined for epiflows objects.

Usage

get_vars(x, ...)

## S3 method for class 'epiflows'
get_vars(x, what = NULL, id = TRUE, vector = FALSE, ...)

set_vars(x, ...)

set_vars(x, name) <- value

## S3 method for class 'epiflows'
set_vars(x, ...)

## S3 replacement method for class 'epiflows'
set_vars(x, name) <- value

Arguments

x

An epiflows object.
...

For set_vars(), any number of variables defined in global_vars() that can be used for mapping or modelling. This is unused in get_vars()
what

a valid character string specifying the variable desired. If 'NULL' (default), the names of the available vars will be returned.
id

a logical. If 'TRUE' (default), the 'id' column of the locations will be the first column of the data frame. if 'FALSE', the variable will be returned with identifiers as row names.
vector

if 'TRUE' the result will be coerced into a vector (or a matrix in the case of coordinates)
name

the name of the variable in global_vars() to assign
value

the name of the column in the locations data

Value

A data frame with the variables requested

Author(s)

Thibaut Jombart, Zhian Kamvar

See Also

global_vars(); make_epiflows(); get_pop_size(); get_id()

Examples

data("Brazil_epiflows")
get_vars(Brazil_epiflows) # defined global variables pointint to column names
get_vars(Brazil_epiflows, "duration_stay")
get_vars(Brazil_epiflows, "duration_stay", vector = TRUE)

Epiflow Global Variables

Description

The metadata in locations such as population size, duration of stay in a given location, date of first and last cases, etc. can be useful in estimating the risk of spread, but not everyone will code their data with identical column names. To facilitate their use in the function estimate_risk_spread(), the epiflows object stores a dictionary of variables in a place called ⁠$vars⁠. We can tell epiflows what variables are important when we create the object.

Usage

global_vars(..., set = FALSE, reset = FALSE)

Arguments

...

quoted varaibles to add to the default variables
set

when TRUE, the variables provided in ... will be added to the global variables. Defaults to FALSE
reset

when TRUE, the global variables are reset to the default variables listed above. Defaults to FALSE

Details

The default varaibles are:

  • coordinates: two columns specifying the lon and lat coordinates

  • pop_size: population size of each location

  • duration_stay: the average duration of stay for each location

  • first_date: the date of first recorded case

  • last_date: the date of the last recorded case

  • num_cases: the number of cases between the first and last date

See Also

make_epiflows(), get_locations(), get_vars(), set_vars(), get_coordinates()

Examples

# see the default varaibles
global_vars()

# Equivalent
getOption("epiflows.vars")

# create an object, specifying these variables
data("YF_locations")
data("YF_flows")
ef <- make_epiflows(flows         = YF_flows, 
                    locations     = YF_locations, 
                    pop_size      = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases     = "num_cases_time_window",
                    first_date    = "first_date_cases",
                    last_date     = "last_date_cases"
                   )
ef


# You will receive an error if a variable is specified incorrectly
YF_locations$random_variable <- runif(nrow(YF_locations))
try({
  ef <- make_epiflows(flows         = YF_flows, 
                      locations     = YF_locations, 
                      Pop_size      = "location_population",
                      duration_stay = "length_of_stay",
                      num_cases     = "num_cases_time_window",
                      first_date    = "first_date_cases",
                      last_date     = "last_date_cases",
                      random        = "random_variable"
                     )
   })


# If you create a new method and need other varaibles, or just want a shorter
# representation, they can be added to your options:

global_vars("random", set = TRUE)

YF_locations$random_variable <- runif(nrow(YF_locations))
ef <- make_epiflows(flows         = YF_flows, 
                    locations     = YF_locations, 
                    pop_size      = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases     = "num_cases_time_window",
                    first_date    = "first_date_cases",
                    last_date     = "last_date_cases",
                    random        = "random_variable"
                   )

# You can also reset the variables
global_vars(reset = TRUE)

Visualise epidemic flows using a grid

Description

This grid plot shows flows between locations by positioning origins and destination in y and x axes, respectively. This function is called when plotting epiflows with type = "grid".

Usage

grid_epiflows(x, color_by = c("from", "to", "none"), ...)

Arguments

x

An epiflows object.
color_by

A character string indicating if flows should be colored by origin (from) or destination (to).
...

arguments passed on to ggplot2::geom_point()

Author(s)

Thibaut Jombart

Create an epiflows object

Description

An epiflows object contains a pair of data frames that provide information about locations and flows between locations.

Usage

make_epiflows(...)

## S3 method for class 'data.frame'
make_epiflows(
  flows,
  locations = NULL,
  from = 1L,
  to = 2L,
  n = 3L,
  id = 1L,
  ...
)

## S3 method for class 'integer'
make_epiflows(inflow, outflow, focus, locations, id = 1L, ...)

## S3 method for class 'numeric'
make_epiflows(inflow, outflow, focus, locations, id = 1L, ...)

Arguments

...

Any number of varaibles that can be used for mapping or modelling. See global_vars() and get_vars() for details.
flows

a data frame where each row represents a flow from one location to the next. This must have at least three columns:

  • Where the flow started (as specified in from, below)

  • Where the flow ended (as specified in to, below)

  • How many cases were involved (as specified in n, below)

locations

a data frame where each row represents a location. This can have any number of columns specifying useful metadata about the location, but it must contain at least one column specifying the location ID used in the flows data frame (as specified by the id argument, below).
from

the column in the flows data frame indicating where the flow started. This can be an integer or character. Default is the first column.
to

the column in the flows data frame indicating where the flow terminated. This can be an integer or character. Default is the second column.
n

the column in the flows data frame indicating how many cases were contained in the flow. This can be an integer or character. Default is the third column.
id

The column to use for the identifier in the locations data frame. This defaults to the first column.
inflow

a named integer or numeric vector specifying the number of cases flowing into a location specified by focus.
outflow

a named integer or numeric vector specifying the number of cases flowing from a location specified by focus.
focus

a character vector specifying the focal location for integer input. This is necessary for integer input to make clear what "outflow" and "inflow" are relative to.

Details

The epiflows object can be constructed using simply a list of locations with optional metadata (similar to a linelist) and a list of flows that describes the number of cases flowing from one location to another. Optional metadata such as coordinates and duration of stay can be included in the linelist for use in estimate_risk_spread() or map_epiflows().

Developer note: object structure

Because a flow of cases from one location to another can be thought of as a contact with a wider scope, the epiflows object inherits from the epicontacts object, constructed via epicontacts::make_epicontacts(). This means that all the methods for subsetting an object of class epicontacts also applies to epiflows, including the use of the function epicontacts::thin(). One caveat is that, internally, the names of the elements within the object do not match the terminology used in epiflows.

Value

An epiflows object in list format with four elements:

  • locations (accessible via get_locations()): a data frame of locations with first column 'id' containing character vector of unique identifiers.

  • flows (accessible via get_flows()): data.frame of flows with first two columns named 'from' and 'to' indicating directed flows between two locations, and a third column named 'n', specifying the number of cases in each

  • vars (accessible via get_vars()). This contains a named list of available variables that can be used in further plotting and/or modelling. Default variables are found in global_vars():

    • coordinates: two columns specifying the lon and lat coordinates

    • pop_size: population size of each location

    • duration_stay: the average duration of stay for each location

    • first_date: the date of first recorded case

    • last_date: the date of the last recorded case

    • num_cases: the number of cases between the first and last date

Author(s)

Zhian Kamvar, Thibaut Jombart

See Also

global_vars() for definitions of global variables, estimate_risk_spread() for modelling, plot.epiflows() for plotting, add_coordinates() for adding coordinates, get_vars() for accession of metadata, get_locations() to access the locations data frame, get_flows() to access the flows data frame.

Examples

## Load data
data(YF_flows)
data(YF_locations)
YF_flows
YF_locations
## Use both to create the epiflows object.
ef <- make_epiflows(flows         = YF_flows, 
                    locations     = YF_locations, 
                    pop_size      = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases     = "num_cases_time_window",
                    first_date    = "first_date_cases",
                    last_date     = "last_date_cases"
                   )
ef
# Access variable information
get_pop_size(ef)
get_vars(ef, "duration_stay")
get_vars(ef, "num_cases")
data(YF_Brazil)
(inflows   <- YF_Brazil$T_O["Espirito Santo", , drop = TRUE])
(outflows  <- YF_Brazil$T_D["Espirito Santo", , drop = TRUE])
(locations <- subset(YF_Brazil$states, location_code == "Espirito Santo", drop = FALSE))
los <- data.frame(location_code    = names(YF_Brazil$length_of_stay), 
                  length_of_stay   = YF_Brazil$length_of_stay,
                  stringsAsFactors = FALSE
                 )
locations <- merge(x   = locations, 
                   y   = los, 
                   by  = "location_code", 
                   all = TRUE)
ef <- make_epiflows(inflow = inflows, 
                    outflow = outflows, 
                    focus = "Espirito Santo", 
                    locations = locations,
                    pop_size = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases = "num_cases_time_window",
                    first_date = "first_date_cases",
                    last_date = "last_date_cases"
                   )
ef

Map flows of people between locations

Description

The function map_epiflows uses leaflet to generate an interactive map displaying flows of people travelling between locations stored in a epiflows object. Note that the object needs to possess geographic coordinates.

Usage

map_epiflows(
  x,
  title = "",
  center = NULL,
  sort = TRUE,
  pal = "YlOrBr",
  adjust_width = TRUE,
  ...
)

Arguments

x

An epiflows object.
title

Plot title.
center

An optional set of coordinates or character string specifying ID to use as the center of the map
sort

a logical. When TRUE (default), the flows will be sorted in order of number of cases on the map so that the largest flows appear on top.
pal

a color palette to pass on to leaflet::colorQuantile(). This can be the name of a viridis or RColorBrewer palette, a vector of hex colors, or a color-generating functon.
adjust_width

a logical specifying if the width of the flows should be adjusted to reflect the number of flows between locations. Defaults to TRUE.
...

Additional parameters (not used).

Value

A leaflet object

Author(s)

Paula Moraga, Pawel Piatkowski, Salla Toikkanen, Zhian Kamvar

Examples

data("Brazil_epiflows")
data("YF_coordinates")
ef <- add_coordinates(Brazil_epiflows, YF_coordinates[-1])
plot(ef)
map_epiflows(ef, center = "Espirito Santo", title = "Flows to and from Brazil")

Various plots for epiflows objects

Description

The plot method for epiflows objects offers types of graphics (argument type):

Usage

## S3 method for class 'epiflows'
plot(x, type = c("map", "network", "grid"), ...)

Arguments

x

an epiflows object.
type

The type of plot to produce (defaults to map).
...

arguments passed on to a given type

Details

  • map: flows are displayed on an interactive map; see map_epiflows for more details

  • network: flows are displayed as a network using the htmlwidget visNetwork and the plotting method for epicontacts objects; see vis_epiflows for more details

  • grid: flows are displayed as a grid between origins and destinations; see grid_epiflows for more details

Author(s)

Salla Toikkanen, Thibaut Jombart, Zhian Kamvar

Examples

data("Brazil_epiflows")

# no coordinates, defaults to network
plot(Brazil_epiflows) 

# grid bubbleplot
plot(Brazil_epiflows, "grid")

# adding coordinates defaults to map
data("YF_coordinates")
ef <- add_coordinates(Brazil_epiflows, YF_coordinates[-1])
plot(ef)

Print method from epiflows objects

Description

Displays a short summary of an epiflows object.

Usage

## S3 method for class 'epiflows'
print(x, ...)

Arguments

x

An epiflows object.
...

Additional parameters (not used).

Author(s)

Zhian N. Kamvar, Thibaut Jombart

Examples

data("Brazil_epiflows")
print(Brazil_epiflows)

Visualise epidemic flows using visNetwork

Description

This function shows flows between locations using a dynamic network visualisation implemented in the package visNetwork, calling the function epicontacts::vis_epicontacts() of the epicontacts package. The thickness of arrows/edges is proportional to the corresponding flows.

Usage

vis_epiflows(x, arrows = TRUE, max_width = 10, ...)

Arguments

x

An epiflows object.
arrows

A logical indicating if arrows should be used to show directionality of the flows.
max_width

A single number indicating the maximum width of an edge (corresponding to the largest flow).
...

Further arguments passed to epicontacts::vis_epicontacts()

Author(s)

Thibaut Jombart

Yellow Fever Data from Brazil; 2016-12 to 2017-05

Description

This data set contains flows to and from five states in Brazil formatted in a list with the following items:

Usage

data("Brazil_epiflows")
  data("YF_coordinates")
  data("YF_locations")
  data("YF_flows")
  data("YF_Brazil")

Format

An object of class list of length 4.

Details

  • ⁠$states⁠: a data frame containing metadata for five Brazilian States: Espirito Santo, Minas Gerais, Rio de Janeiro, Sao Paulo, and Southeast Brazil

    • ⁠$location_code⁠ : names of the states

    • ⁠$location_population⁠ : population size for each state

    • ⁠$num_cases_time_window⁠ : number of cases recorded between 2016-12 and 2017-05

    • ⁠$first_date_cases⁠ : date of first disease case in the given location in ISO 8601 format

    • ⁠$last_date_cases⁠ : date of last disease case in the given location in ISO 8601 format

  • ⁠$T_D⁠ A matrix containing the number of travellers from the infectious location visiting other locations

  • ⁠$T_O⁠ A matrix containing the number of travellers visiting the infectious location

  • ⁠$length_of_stay⁠ A named vector containing the average length of stay in days of travellers from other locations visiting the infectious locations.

References

Dorigatti I, Hamlet A, Aguas R, Cattarino L, Cori A, Donnelly CA, Garske T, Imai N, Ferguson NM. International risk of yellow fever spread from the ongoing outbreak in Brazil, December 2016 to May 2017. Euro Surveill. 2017;22(28):pii=30572. DOI: doi:10.2807/1560-7917.ES.2017.22.28.30572

See Also

make_epiflows() for transformation to an epiflows object estimate_risk_spread()

Examples

# This is an example of an epiflows object
data("Brazil_epiflows")
Brazil_epiflows

# The above data was constructed from a data frame containing flows and 
# one containing location metadata
data("YF_flows")
data("YF_locations")
ef <- make_epiflows(flows         = YF_flows, 
                    locations     = YF_locations, 
                    pop_size      = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases     = "num_cases_time_window",
                    first_date    = "first_date_cases",
                    last_date     = "last_date_cases"
                   )

# Both of the above data frames were constructed like so:

data("YF_Brazil")

# Create the flows data frame
from  <- as.data.frame.table(YF_Brazil$T_D, stringsAsFactors = FALSE)
to    <- as.data.frame.table(t(YF_Brazil$T_O), stringsAsFactors = FALSE)
flows <- rbind(from, to)
colnames(flows) <- c("from", "to", "n")

## Create the locations data frame
los <- data.frame(location_code    = names(YF_Brazil$length_of_stay), 
                  length_of_stay   = YF_Brazil$length_of_stay,
                  stringsAsFactors = FALSE
                 )
locations <- merge(x   = YF_Brazil$states, 
                   y   = los, 
                   by  = "location_code", 
                   all = TRUE)

## Use both to create the epiflows object.
ef <- make_epiflows(flows, 
                    locations, 
                    pop_size = "location_population",
                    duration_stay = "length_of_stay",
                    num_cases = "num_cases_time_window",
                    first_date = "first_date_cases",
                    last_date = "last_date_cases"
)