Graph signal processing in R.
Install the devtools package if you haven’t already.
install.packages("devtools")To install the development package, type the following at the R command line:
devtools::install_github("fabnavarro/gasper")
library(gasper)To install the CRAN version of the package, type the following:
install.packages("gasper")To obtain the complete list of package functions, simply type
help(package = "gasper")See the package vignette or documentation for more details. You could also build and see the vignette associated with the package using the following lines of code
devtools::install_github("fabnavarro/gasper", build_vignettes = TRUE)
library(gasper)Then, to view the vignette
vignette("gasper_vignette")For an illustration of the features of the package, you can also refer to the following repo SGWT-SURE which provides an effective generalization of the Stein Unbiased Risk Estimate (SURE) for signal denoising/regression on graphs using Spectral Graph Wavelet Transform.
The package also provides an interface to the SuiteSparse Matrix Collection, which is a large and actively growing set of sparse matrix benchmarks gathered from a broad spectrum of applications (for details see https://sparse.tamu.edu/).
Included in the package, the SuiteSparseData dataset contains data
from the SuiteSparse Matrix Collection. The structure of this dataframe
mirrors the structure presented on the SuiteSparse Matrix Collection
website, allowing users to query and explore the dataset directly within
R.
Here is a sample of the SuiteSparseData dataset, showing the first 15
rows of the table:
SuiteSparseData_subset <- head(SuiteSparseData, 15)| ID | Name | Group | Rows | Cols | Nonzeros | Kind | Date |
|---|---|---|---|---|---|---|---|
| 1 | 1138_bus | HB | 1138 | 1138 | 4054 | Power Network Problem | 1985 |
| 2 | 494_bus | HB | 494 | 494 | 1666 | Power Network Problem | 1985 |
| 3 | 662_bus | HB | 662 | 662 | 2474 | Power Network Problem | 1985 |
| 4 | 685_bus | HB | 685 | 685 | 3249 | Power Network Problem | 1985 |
| 5 | abb313 | HB | 313 | 176 | 1557 | Least Squares Problem | 1974 |
| 6 | arc130 | HB | 130 | 130 | 1037 | Materials Problem | 1974 |
| 7 | ash219 | HB | 219 | 85 | 438 | Least Squares Problem | 1974 |
| 8 | ash292 | HB | 292 | 292 | 2208 | Least Squares Problem | 1974 |
| 9 | ash331 | HB | 331 | 104 | 662 | Least Squares Problem | 1974 |
| 10 | ash608 | HB | 608 | 188 | 1216 | Least Squares Problem | 1974 |
| 11 | ash85 | HB | 85 | 85 | 523 | Least Squares Problem | 1974 |
| 12 | ash958 | HB | 958 | 292 | 1916 | Least Squares Problem | 1974 |
| 13 | bcspwr01 | HB | 39 | 39 | 131 | Power Network Problem | 1981 |
| 14 | bcspwr02 | HB | 49 | 49 | 167 | Power Network Problem | 1981 |
| 15 | bcspwr03 | HB | 118 | 118 | 476 | Power Network Problem | 1981 |
Here’s an example to retrieve all undirected weighted graphs with the number of columns and rows between 50 and 150:
filtered_mat <- SuiteSparseData[SuiteSparseData$Kind == "Undirected Weighted Graph" &
SuiteSparseData$Rows >= 50 & SuiteSparseData$Rows <= 150 &
SuiteSparseData$Cols >= 50 & SuiteSparseData$Cols <= 150, ]| ID | Name | Group | Rows | Cols | Nonzeros | Kind | Date | |
|---|---|---|---|---|---|---|---|---|
| 1506 | 1506 | Journals | Pajek | 124 | 124 | 12068 | Undirected Weighted Graph | 2000 |
| 1519 | 1519 | Sandi_authors | Pajek | 86 | 86 | 248 | Undirected Weighted Graph | 1999 |
| 2400 | 2400 | lesmis | Newman | 77 | 77 | 508 | Undirected Weighted Graph | 1993 |
| 2858 | 2858 | breasttissue_10NN | ML_Graph | 106 | 106 | 1412 | Undirected Weighted Graph | 2020 |
| 2872 | 2872 | iris_dataset_30NN | ML_Graph | 150 | 150 | 5518 | Undirected Weighted Graph | 2020 |
The download_graph function allows to download a test matrix from this
collection. For example:
matrixname <- "usroads-48"
groupname <- "Gleich"
download_graph(matrixname,groupname)
attributes(`usroads-48`)
#> $names
#> [1] "sA" "xy" "dim" "temp"usroads-48 is composed of the sparse matrix sA (in compressed sparse
column format), coordinates xy (if present, in a data.frame), dim
the number of rows, columns and numerically nonzero elements and temp
path to the temporary directory where the matrix and downloaded files
(including singular values if requested) are stored. Information about
the matrix can be display via
file.show(paste(usroads-48$temp,"usroads-48",sep="")) or in the
console:
cat(readLines(paste(`usroads-48`$temp,"usroads-48",sep="")), sep = "\n")
#> %%MatrixMarket matrix coordinate pattern symmetric
#> %-------------------------------------------------------------------------------
#> % UF Sparse Matrix Collection, Tim Davis
#> % http://www.cise.ufl.edu/research/sparse/matrices/Gleich/usroads-48
#> % name: Gleich/usroads-48
#> % [Continental US road network (with xy coordinates)]
#> % id: 2332
#> % date: 2010
#> % author: D. Gleich
#> % ed: T. Davis
#> % fields: name title A id date author ed kind aux
#> % aux: coord
#> % kind: undirected graph
#> %-------------------------------------------------------------------------------
#> 126146 126146 161950download_graph function has an optional svd argument; setting “svd =
TRUE” downloads a “.mat” file containing the singular values of the
matrix, if available. To access the temporary folder use, for example,
list.files(`usroads-48`$temp)
#> [1] "usroads-48" "usroads-48_coord.mtx" "usroads-48.mtx"In addition, the get_graph_info function allows to retrieve detailed
information about the matrix from the SuiteSparse Matrix Collection
website (rvest package needs to be installed to use it). This function
extracts and formats various properties and metadata associated with the
matrix (i.e., it fetches the two to three tables with
“MatrixInformation,” “MatrixProperties” and, if available,
“SVDStatistics”), providing a convenient way to access this overview of
the graph directly within R. Here is how you can use it:
graph_info <- get_graph_info(matrixname, groupname)
graph_info
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The download_graph function has an optional argument add_info which,
when set to TRUE, automatically calls get_graph_info and appends the
retrieved information to the output of download_graph. This makes it
easy to get both the graph data and its associated information in a
single function call.
downloaded_graph <- download_graph(matrixname, groupname, add_info = TRUE)
downloaded_graph$infoIt is also possible to plot a (planar) graph and plot signals defined on top of it. For example:
f <- sin(rnorm(nrow(`usroads-48`$xy)))
plot_graph(`usroads-48`, size = 0.05)
plot_signal(`usroads-48`, f, size = f/4)
In cases where these coordinates are not supplied, plot_graph employs
simple spectral graph embedding to calculate some node coordinates
(nodes that are connected or share structural similarities in the graph
are placed close to each other in the spectral drawing). This is done
using the function spectral_coords, which computes the spectral
coordinates based on the eigenvectors associated with the smallest
non-zero eigenvalues of the graph’s Laplacian.
matrixname <- "delaunay_n10"
groupname <- "DIMACS10"
download_graph(matrixname,groupname)
attributes(delaunay_n10)
#> $names
#> [1] "sA" "dim" "temp"
plot_graph(delaunay_n10)
plot_signal(delaunay_n10,
cos(1:nrow(delaunay_n10$sA)))
graph_info <- get_graph_info(matrixname, groupname)
graph_info
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