Package 'abstr'

Convert geographic ('sf') representation of OD data to 'JSON list' structure

Description

This function takes outputs from ab_scenario() and returns a list that can be saved as a JSON file for import into A/B Street.

Usage

ab_json(
  desire_lines,
  mode_column = NULL,
  time_fun = ab_time_normal,
  scenario_name = "test",
  default_purpose = "Work",
  ...
)

Arguments

desire_lines	OD data represented as geographic lines created by ab_scenario().
mode_column	The column name in the desire lines data that contains the mode of transport. "mode_baseline" by default.
time_fun	The function used to calculate departure times. ab_time_normal() by default.
scenario_name	The name of the scenario to appear in A/B Street. The default value is "test", which generates a message to tell you to think of a more imaginative scenario name!
default_purpose	In case a purpose column is not present in the input, or there are missing values in the purpose column, this argument sets the default, fallback purpose, as "Work" by default, reflecting the prevalence of work-based data and thinking in transport models.
...	Additional arguments to pass to ab_json()

Details

Note: the departure time in seconds is multiplied by 10000 on conversion to a .json list object for compatibility with the A/B Street schema.

Value

A list that can be saved as a JSON file with ab_save()

Examples

# Starting with tabular data
od = leeds_od
od[[1]] = c("E02006876")
zones = leeds_zones
ablines = ab_scenario(od, zones = zones)
ab_list = ab_json(ablines, mode_column = "mode", scenario_name = "test")
ab_list$scenario
f = tempfile(fileext = ".json")
ab_save(ab_list, f)
readLines(f)[1:30]

# Starting with JSON data from A/B Street (multiple trips per person)
f = system.file("extdata/minimal_scenario2.json", package = "abstr")
desire_lines = ab_sf(f)
desire_lines
json_list = ab_json(desire_lines)
json_list

---

Save OD data as JSON files for import into A/B Street

Description

Save OD data as JSON files for import into A/B Street

Usage

ab_save(x, f)

Arguments

x	A list object produced by ab_scenario()
f	A filename, e.g. new_scenario.json

Value

A JSON file containing scenarios from ab_scenario()

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Generate A/B Street Scenario objects by disaggregating aggregate OD data

Description

This function takes a data frame representing origin-destination trip data in 'long' form, zones and, optionally, buildings from where trips can start and end as inputs.

Usage

ab_scenario(
  od,
  zones,
  zones_d = NULL,
  origin_buildings = NULL,
  destination_buildings = NULL,
  pop_var = 3,
  time_fun = ab_time_normal,
  output = "sf",
  modes = c("Walk", "Bike", "Transit", "Drive"),
  ...
)

Arguments

od	Origin destination data with the first 2 columns containing zone code of origin and zone code of destination. Subsequent columns should be mode names such as All and Walk, Bike, Transit, Drive, representing the number of trips made by each mode of transport for use in A/B Street.
zones	Zones with IDs that match the desire lines. Class: sf.
zones_d	Optional destination zones with IDs that match the second column of the od data frame (work in progress)
origin_buildings	Polygons where trips will originate (sf object)
destination_buildings	Polygons where trips can end, represented as sf object
pop_var	The variable containing the total population of each desire line.
time_fun	The function used to calculate departure times. ab_time_normal() by default.
output	Which output format? "sf" (default) and "json_list" return R objects. A file name such as "baseline.json" will save the resulting scenario to a file.
modes	Character string containing the names of the modes of travel to include in the outputs. These must match column names in the od input data frame. The default is c("Walk", "Bike", "Drive", "Transit"), matching the mode names allowed in the A/B Street scenario schema.
...	Additional arguments to pass to ab_json()

Value

An sf object by default representing individual trips between randomly selected points (or buildings when available) between the zones represented in the OD data.

Examples

od = leeds_od
zones = leeds_zones
od[[1]] = c("E02006876")
ablines = ab_scenario(od, zones = zones)
plot(ablines)
table(ablines$mode)
colSums(od[3:7]) # 0.17 vs 0.05 for ab_scenario
ablines = ab_scenario(od, zones = zones, origin_buildings = leeds_buildings)
plot(leeds_zones$geometry)
plot(leeds_buildings$geometry, add = TRUE)
plot(ablines["mode"], add = TRUE)
ablines_json = ab_json(ablines, scenario_name = "test")
od = leeds_desire_lines
names(od)[4:6] = c("Walk", "Bike", "Drive")
ablines = ab_scenario(
  od = od,
  zones = leeds_site_area,
  zones_d = leeds_zones,
  origin_buildings = leeds_houses,
  destination_buildings = leeds_buildings,
  output = "sf"
)
plot(ablines)
plot(ablines$geometry)
plot(leeds_site_area$geometry, add = TRUE)
plot(leeds_buildings$geometry, add = TRUE)

---

Convert JSON representation of trips from A/B Street into an 'sf' object

Description

This function takes a path to a JSON file representing an A/B Street scenario, or an R representation of the JSON in a list, and returns an sf object with the same structure as objects returned by ab_scenario().

Usage

ab_sf(json)

Arguments

json	Character string or list representing a JSON file or list that has been read into R and converted to a data frame.

Details

Note: the departure time in seconds is divided by 10000 on conversion to represent seconds, which are easier to work with that 10,000th of a second units.

Value

An sf data frame representing travel behaviour scenarios from, and which can be fed into, A/B Street. Contains the following columns: person (the ID of each agent in the simulation), departure (seconds after midnight of the travel starting), mode (the mode of transport, being Walk, Bike, Transit and Drive), purpose (what the trip was for, e.g. Work), and geometry (a linestring showing the start and end point of the trip/stage).

Examples

file_name = system.file("extdata/minimal_scenario2.json", package = "abstr")
ab_sf(file_name)
json = jsonlite::read_json(file_name, simplifyVector = TRUE)
ab_sf(json)

---

Generate times for A/B scenarios

Description

Generate times for A/B scenarios

Usage

ab_time_normal(hr = 8.5, sd = 0.5, n = 1)

Arguments

hr	Number representing the hour of day of departure (on average). 8.5, for example represents 08:30.
sd	The standard deviation in hours of the distribution
n	The number of numbers representing times to return

Value

An integer representing the time since midnight in seconds

Examples

time_lunch = ab_time_normal(hr = 12.5, sd = 0.25)
time_lunch
# Back to a formal time class
as.POSIXct(trunc(Sys.time(), units="days") + time_lunch)
time_morning = ab_time_normal(hr = 8.5, sd = 0.5)
as.POSIXct(trunc(Sys.time(), units="days") + time_morning)
time_afternoon = ab_time_normal(hr = 17, sd = 0.75)
as.POSIXct(trunc(Sys.time(), units="days") + time_afternoon)

---

Datasets from Leeds

Description

These datasets represent data from the case study city of Leeds.

---

Example OSM Buildings Table for Montlake

Description

Each row of this table contains a building that exists within a zone in the montlake_zones table.

Format

A sf dataframe with columns:

osm_way_id

OSM ID assigned to each building.

name

OSM name assigned to each building (might be NA).

building

OSM building category assigned to each building.

geometry

Simple feature collection (sfc) contain multipolygons, each representing the boundaries of a building.

Details

These buildings were retrieved using osmextract::oe_read(). See the code used to create this data in data-raw/montlake-test-data.R.

Source

OpenStreetMap

Examples

library(sf)
names(montlake_buildings)
head(montlake_buildings$osm_way_id)
head(montlake_buildings$name)
head(montlake_buildings$building)
nrow(montlake_buildings)
plot(montlake_buildings)

---

Example OD Table for Montlake

Description

Each row of this table contains a count of how many trips started in column o_id and ended in column d_id according to different modes. This example table has modes that match what A/B Street currently uses: "Drive", "Transit", "Bike", and "Walk".

Usage

montlake_od

Format

A data frame with columns:

o_id

Trip origin zone ID (must match an ID in montlake_zone).

d_id

Trip destination zone ID (must match an ID in montlake_zone).

Drive

Count of how many trips were made using cars.

Transit

Count of how many trips were made using public transit.

Bike

Count of how many trips were made using bikes.

Walk

Count of how many trips were made on foot.

Details

See the code used to create this data in "data-raw/montlake-test-data.R"

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Example Zones Table for Montlake

Description

Each row of this table contains the zone ID and geometry for a TAZ near Montlake. Includes all zones that start or end within the Montlake boundary and have at least 25 trips across all modes of transit in montlake_od.

Usage

montlake_zones

Format

A sf dataframe with columns:

id

Zone ID (must match o_id or d_id in montlake_od).

geometry

Simple feature collection (sfc) contain multipolygons, each representing the boundaries of a TAZ near Montlake.

Details

See the code used to create this data in "data-raw/montlake-test-data.R"

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Example Activity data for São Paulo

Description

Each row of this table contains a single trip of people in the São Paulo city. sao_paulo_activity_df_2 represents the movement of 2 people, sao_paulo_activity_df_20 represents the movement of 20 people.

Usage

sao_paulo_activity_df_20

Format

A data frame with columns:

ID_PESS

Person identifier.

CO_O_X

Origin coordinate X.

CO_O_Y

Origin coordinate Y.

CO_D_X

Destination coordinate X.

CO_D_Y

Destination coordinate Y.

MODOPRIN

Main mode.

H_SAIDA

Departure hour.

MIN_SAIDA

Departure minute.

Details

See the code used to create this data, and the full open dataset with 128 variables, the file data-raw/sao-paulo-activity-data.R in the package's GitHub repo.

Examples

dim(sao_paulo_activity_df_20)
names(sao_paulo_activity_df_20)
head(sao_paulo_activity_df_20)
dim(sao_paulo_activity_df_2)
names(sao_paulo_activity_df_2)
head(sao_paulo_activity_df_2)

---

Example Activity data for São Paulo

Description

Each row of this table contains a single trip of people in the São Paulo city. sao_paulo_activity_sf_2 represents the movement of 2 people, sao_paulo_activity_sf_20 represents the movement of 20 people.

Usage

sao_paulo_activity_sf_20

Format

A data frame with columns:

person

Person identifier.

departure

Departure time in seconds past midnight

mode

Mode of travel in A/B Street terms

purpose

Purpose of travel in A/B Street terms

geometry

Geometry of the linestring representing the OD pair

Details

See the code used to create this data, and the full open dataset with 128 variables, the file data-raw/sao-paulo-activity-data.R in the package's GitHub repo.

Examples

dim(sao_paulo_activity_sf_20)
names(sao_paulo_activity_sf_20)
head(sao_paulo_activity_sf_20)
table(sao_paulo_activity_sf_20$mode)
table(sao_paulo_activity_sf_20$purpose)
dim(sao_paulo_activity_sf_2)
names(sao_paulo_activity_sf_2)
head(sao_paulo_activity_sf_2)

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