Package {griddy}

Title: Geospatial Distribution Dynamics for Simple Features
Version: 0.1.0
Description: Tools for exploratory geospatial distribution dynamics with 'sf' objects and tidy data. Provides pooled and time-specific classification of longitudinal spatial values, classic discrete Markov transition matrices, spatial Markov matrices conditioned on spatial-lag classes, endpoint and adjacent rank mobility summaries, and 'ggplot2' visualizations. Methods follow Rey (2001) <doi:10.1111/j.1538-4632.2001.tb00444.x> and Rey et al. (2016) <doi:10.1007/s10109-016-0234-x>; design is inspired by the Python 'PySAL' 'giddy' package https://pysal.org/giddy/.
URL: https://github.com/dshkol/griddy, https://dshkol.github.io/griddy/
BugReports: https://github.com/dshkol/griddy/issues
License: MIT + file LICENSE
Encoding: UTF-8
Language: en-US
RoxygenNote: 7.3.2
Depends: R (≥ 4.2)
Imports: dplyr, ggplot2, rlang, scales, sf, spdep, tibble, tidyr
Suggests: cancensus, knitr, microbenchmark, pkgdown, rmarkdown, sfdep, spData, testthat (≥ 3.0.0), tidycensus
VignetteBuilder: knitr
Config/testthat/edition: 3
LazyData: true
NeedsCompilation: no
Packaged: 2026-05-27 16:36:40 UTC; dmitryshkolnik
Author: Dmitry Shkolnik [aut, cre]
Maintainer: Dmitry Shkolnik <shkolnikd@gmail.com>
Repository: CRAN
Date/Publication: 2026-05-30 13:30:02 UTC

griddy: Geospatial Distribution Dynamics

Description

Tidy helpers for exploratory geospatial distribution dynamics.

Author(s)

Maintainer: Dmitry Shkolnik shkolnikd@gmail.com

See Also

Useful links:

Class Intervals Used By A griddy Object

Description

Class Intervals Used By A griddy Object

Usage

class_intervals(x, ...)

Arguments

x

A griddy result object.

...

Reserved for future methods.

Value

A tibble of class intervals when available.

Examples


panel <- data.frame(id = rep(1:3, each = 2), year = rep(2020:2021, 3), value = 1:6)
classes <- classify_dynamics(panel, id, year, value, k = 3)
class_intervals(classes)

Classify Longitudinal Values For Distribution Dynamics

Description

Converts numeric values in a long panel into ordered classes suitable for transition analysis.

Usage

classify_dynamics(
  data,
  id,
  time,
  value,
  method = c("pooled_quantile", "time_quantile", "fixed", "existing"),
  k = 5,
  breaks = NULL,
  labels = NULL
)

Arguments

data

A data frame or sf object in long format.

id, time, value

Columns identifying spatial unit, time, and value.

method

Classification method. "pooled_quantile" uses one set of quantile breaks across all periods. "time_quantile" uses period-specific ranks. "fixed" uses user-supplied breaks. "existing" treats value as an already classified state.

k

Number of quantile classes.

breaks

Breaks for method = "fixed".

labels

Optional class labels.

Value

A data frame or sf object with a class column and class grd_classes.

Examples


panel <- data.frame(
  id = rep(letters[1:4], each = 3),
  year = rep(2020:2022, times = 4),
  value = c(8, 9, 11, 10, 12, 13, 15, 14, 16, 20, 22, 25)
)

classes <- classify_dynamics(panel, id, year, value, k = 3)
classes
class_intervals(classes)

Spatial Lag Intervals Used By A Spatial Markov Object

Description

Spatial Lag Intervals Used By A Spatial Markov Object

Usage

lag_intervals(x)

Arguments

x

A grd_spatial_markov object.

Value

A tibble of spatial-lag class intervals.

Examples


panel <- data.frame(
  id = rep(1:4, each = 2),
  year = rep(2020:2021, times = 4),
  value = c(1, 2, 2, 3, 4, 3, 5, 6)
)
grid <- sf::st_sf(
  id = 1:4,
  geometry = sf::st_make_grid(
    sf::st_bbox(c(xmin = 0, ymin = 0, xmax = 2, ymax = 2)),
    n = c(2, 2)
  )
) |>
  dplyr::mutate(
    nb = sfdep::st_contiguity(geometry),
    wt = sfdep::st_weights(nb)
  )
spatial <- spatial_markov(panel, id, year, value, geometry = grid, k = 2)
lag_intervals(spatial)

Estimate Classic Markov Transition Dynamics

Description

Estimates transition counts and probabilities between adjacent periods for a classified long panel.

Usage

markov_dynamics(classes, id, time, state = class)

Arguments

classes

A classified data frame from classify_dynamics() or any data frame with ID, time, and state columns.

id, time, state

Columns identifying spatial unit, time, and state.

Value

A grd_markov object.

Examples


panel <- data.frame(
  id = rep(letters[1:4], each = 3),
  year = rep(2020:2022, times = 4),
  value = c(8, 9, 11, 10, 12, 13, 15, 14, 16, 20, 22, 25)
)

classes <- classify_dynamics(panel, id, year, value, k = 3)
markov <- markov_dynamics(classes, id, year, class)

markov
transition_matrix(markov)
steady_state(markov)

Plot Rank Mobility

Description

Plot Rank Mobility

Usage

plot_rank_mobility(x)

Arguments

x

A grd_rank_mobility object returned by rank_mobility().

Value

A ggplot object.

Plot Spatial Markov Matrices

Description

Plot Spatial Markov Matrices

Usage

plot_spatial_markov(x)

Arguments

x

A grd_spatial_markov object.

Value

A ggplot object.

Examples


panel <- data.frame(
  id = rep(1:4, each = 2),
  year = rep(2020:2021, times = 4),
  value = c(1, 2, 2, 3, 4, 3, 5, 6)
)
grid <- sf::st_sf(
  id = 1:4,
  geometry = sf::st_make_grid(
    sf::st_bbox(c(xmin = 0, ymin = 0, xmax = 2, ymax = 2)),
    n = c(2, 2)
  )
) |>
  dplyr::mutate(
    nb = sfdep::st_contiguity(geometry),
    wt = sfdep::st_weights(nb)
  )
spatial <- spatial_markov(panel, id, year, value, geometry = grid, k = 2)
plot_spatial_markov(spatial)

Plot A Transition Matrix

Description

Plot A Transition Matrix

Usage

plot_transition_matrix(x)

Arguments

x

A grd_markov object.

Value

A ggplot object.

Examples


panel <- data.frame(id = rep(1:4, each = 2), year = rep(2020:2021, 4), value = 1:8)
markov <- panel |>
  classify_dynamics(id, year, value, k = 2) |>
  markov_dynamics(id, year, class)

plot_transition_matrix(markov)

Compute Rank Mobility

Description

Computes simple rank changes for map-ready exploratory analysis.

Usage

rank_mobility(
  data,
  id,
  time,
  value,
  compare = c("endpoint", "adjacent"),
  descending = TRUE
)

Arguments

data

A long data frame or sf object.

id, time, value

Columns identifying spatial unit, time, and value.

compare

"endpoint" compares first and last observed periods per unit. "adjacent" compares adjacent periods.

descending

If TRUE, larger values receive better ranks.

Value

A grd_rank_mobility data frame or sf object.

Examples


panel <- data.frame(
  id = rep(letters[1:4], each = 3),
  year = rep(2020:2022, times = 4),
  value = c(8, 9, 11, 10, 12, 13, 15, 14, 16, 20, 22, 25)
)

rank_mobility(panel, id, year, value)

Estimate Spatial Markov Transition Dynamics

Description

Estimates transition matrices conditioned on the class of each unit's spatial lag at the start of the transition period.

Usage

spatial_markov(
  data,
  id,
  time,
  value,
  geometry = NULL,
  listw = NULL,
  nb = NULL,
  k = 5,
  lag_k = k,
  class_method = c("pooled_quantile", "time_quantile", "fixed"),
  zero.policy = TRUE
)

Arguments

data

A long data frame or sf object.

id, time, value

Columns identifying spatial unit, time, and value.

geometry

An sf tibble with one row per spatial unit (a single time slice's geography), carrying nb and wt list-columns produced by sfdep::st_contiguity() and sfdep::st_weights(). The preferred input.

listw

A row-standardized spdep listw object. Accepted for compatibility with prior workflows; use geometry for new code.

nb

A spdep neighbor list, used only when both geometry and listw are NULL. Converted with spdep::nb2listw(style = "W").

k

Number of value classes.

lag_k

Number of spatial-lag classes.

class_method

Value classification method passed to classify_dynamics().

zero.policy

Passed to spdep lag/weight helpers.

Value

A grd_spatial_markov object.

Examples


panel <- data.frame(
  id = rep(1:4, each = 3),
  year = rep(2020:2022, times = 4),
  value = c(1, 2, 3, 2, 3, 4, 4, 3, 5, 5, 6, 7)
)

grid <- sf::st_sf(
  id = 1:4,
  geometry = sf::st_make_grid(
    sf::st_bbox(c(xmin = 0, ymin = 0, xmax = 2, ymax = 2)),
    n = c(2, 2)
  )
) |>
  dplyr::mutate(
    nb = sfdep::st_contiguity(geometry),
    wt = sfdep::st_weights(nb)
  )

spatial <- spatial_markov(panel, id, year, value, geometry = grid, k = 2)

spatial
lag_intervals(spatial)
transition_matrix(spatial, "count", lag_class = "Q1")

Estimate Stationary Distribution

Description

Estimate Stationary Distribution

Usage

steady_state(x)

Arguments

x

A grd_markov object or transition probability matrix.

Value

A numeric vector.

Examples


prob <- matrix(c(0.8, 0.2, 0.3, 0.7), nrow = 2, byrow = TRUE)
steady_state(prob)

Extract A Transition Matrix

Description

Extract A Transition Matrix

Usage

transition_matrix(x, type = c("probability", "count"), lag_class = NULL)

Arguments

x

A grd_markov or grd_spatial_markov object.

type

"probability" or "count".

lag_class

Optional lag class for grd_spatial_markov.

Value

A matrix.

Examples


panel <- data.frame(
  id = rep(letters[1:4], each = 3),
  year = rep(2020:2022, times = 4),
  value = c(8, 9, 11, 10, 12, 13, 15, 14, 16, 20, 22, 25)
)
markov <- panel |>
  classify_dynamics(id, year, value, k = 3) |>
  markov_dynamics(id, year, class)

transition_matrix(markov, "count")

US State Per-Capita Personal Income, 1929-2009

Description

Per-capita personal income for the 48 contiguous US states in nominal dollars. Mirrors the canonical usjoin panel used in PySAL giddy and the spatial Markov literature, so examples and validation in this package are directly comparable to that reference work.

Usage

usjoin

Format

A tibble with 3,888 rows (48 states x 81 years) and 4 columns:

name

State name.

state_fips

State FIPS code, integer.

year

Year, integer 1929 to 2009.

income

Nominal per-capita personal income, integer USD.

Source

PySAL libpysal examples/us_income/usjoin.csv. The original series is constructed from US Bureau of Economic Analysis state personal income tables. See https://github.com/pysal/libpysal.

References

Rey, S. J. (2001). Spatial empirics for economic growth and convergence. Geographical Analysis, 33(3), 195-214.

Rey, S. J., Kang, W., & Wolf, L. (2016). The properties of tests for spatial effects in discrete Markov chain models of regional income distribution dynamics. Journal of Geographical Systems, 18(4), 377-398.

Examples

data(usjoin)
head(usjoin)
range(usjoin$year)

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