In gregmacfarlane/ctpp_flows: Census transportation planning package flows

knitr::opts_chunk$set(
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library(tidyverse)

ctppflows

The goal of ctppflows is to provide tract level home-work flow data from the Census Transportation Planning Package (CTPP) in a much more convenient format for R users, particularly those without a Microsoft Access license.

The entire tract dataset is included in the package as a documented R object, and the package also contains helper functions for properly calculating aggregate flows and their margins of error.

Installation

You can install the development version of ctpp_flows from GitHub with:

# install.packages("devtools")
devtools::install_github("gregmacfarlane/ctpp_flows")

Example

After installing the library, the ctpp_flows dataset is available as a tibble lazy-loaded into your environment.

library(ctppflows)

# load 
ctpp_flows

The aggregate_flows function will aggregate the flows to a state or county. The aggregated margin of error is computed as

$$ \sqrt{\sum_{i=1}^N MOE_i^2}$$

aggregate_flows("state")

The results can then be passed into other R formatting functions. For instance, we could make a plot of where workers into Salt Lake County reside.

# get workplaces in salt lake county
sl_workers <- ctpp_flows %>%
  mutate(county = str_c(get_state(workplace), get_county(workplace))) %>%
  filter(county == "49035") %>%
  filter(flow > 50) %>%
  group_by(residence) %>%
  summarise(flow = sum(flow))

ut_tr <- tigris::tracts("Utah", class = "sf", progress_bar = FALSE) %>%
  select(GEOID) %>%
  left_join(sl_workers, by = c("GEOID" = "residence"))

ggplot(ut_tr %>% filter(flow > 0), aes(fill = log(flow))) +
  geom_sf() + scale_fill_viridis_b()