create_1D_mapper_object: One-Dimensional Mapper

In mappeR: Construct Mapper Graphs for Topological and Exploratory Data Analysis

One-Dimensional Mapper

Description

Run Mapper using a one-dimensional filter, a cover of the codomain of intervals, and a clusterer.

Usage

create_1D_mapper_object(
  data,
  dists,
  lens,
  cover,
  clusterer = global_hierarchical_clusterer("single", dists)
)

Arguments

data	A data frame.
dists	A distance matrix associated to the data frame. Can be a dist object or matrix. The names of the rows of the data points in the distance matrix need to match the names of the data points in data.
lens	The result of a function applied to the rows of data (a matrix, data.frame, list, or vector), or a function which accepts a data point and outputs a result. If the former, there should be one value per observation in the original data frame, and, if the values are not named, they should be in the same order as their inputs in the original data frame.
cover	An n \times 2 matrix of interval left and right endpoints; rows should be intervals and columns left and right endpoints (in that order).
clusterer	A function which accepts a list of distance matrices as input, and returns the results of clustering done on each distance matrix; that is, it should return a list of named vectors, whose name are the names of data points and whose values are cluster assignments (integers). If this value is omitted, then trivial clustering will be done.

Value

A list of two data frames, nodes and edges, which contain information about the Mapper graph constructed from the given parameters.

The node data frame consists of:

• id: vertex ID

• cluster_size: number of data points in cluster

• medoid: the name of the medoid of the vertex

• mean_dist_to_medoid: mean distance to medoid of cluster

• max_dist_to_medoid: max distance to medoid of cluster

• cluster_width: maximum pairwise distance within cluster

• wcss: sum of squares of distances to cluster medoid

• data: names of data points in cluster

• patch: level set ID

The edge data frame contains consists of:

• source: vertex ID of edge source

• target: vertex ID of edge target

• weight: Jaccard index of edge; this is the size of the intersection between the vertices divided by the union

• overlap_data: names of data points in overlap

• overlap_size: number of data points overlap

Examples

# Create noisy circle data
data = data.frame(x = sapply(1:1000, function(x) cos(x)) + runif(1000, 0, .25),
 y = sapply(1:1000, function(x) sin(x)) + runif(1000, 0, .25))

# Project to horizontal axis as lens
projx = data$x

# Create a one-dimensional cover
num_bins = 5
percent_overlap = 25
cover = create_width_balanced_cover(min(projx), max(projx), num_bins, percent_overlap)

# Build Mapper object
create_1D_mapper_object(data, dist(data), projx, cover)

mappeR documentation built on Jan. 27, 2026, 9:06 a.m.