increase_na_percentage

Strategically introduces NA values into a distance matrix while maintaining symmetry.
New NA values are added preferentially farther from the diagonal to simulate real-world
measurement patterns where distant pairs are more likely to be unmeasured.

An implementation of the TopoLow algorithm, a novel, physics-inspired method for
antigenic cartography. TopoLow addresses significant challenges in mapping antigenic relationships,
especially from sparse and noisy experimental data. The package transforms cross-reactivity and
binding affinity measurements into accurate spatial representations in a phenotype space.
Key features include:
* Robust Mapping from Sparse Data: Effectively creates complete and consistent maps even with high
proportions of missing data (e.g., >95%).
* Physics-Inspired Optimization: Models antigens as particles connected by springs (for measured
interactions) and subject to repulsive forces (for missing interactions), reducing the need for
complex gradient computations.
* Automatic Dimensionality Detection: Employs a likelihood-based approach to determine the optimal
number of dimensions for the antigenic map, avoiding distortions common in methods with fixed low dimensions.
* Noise and Bias Reduction: Naturally mitigates experimental noise and bias through its network-based,
error-dampening mechanism.
* Antigenic Velocity Calculation: Introduces and quantifies "antigenic velocity," a vector that describes
the rate and direction of antigenic drift for each pathogen isolate. This can help identify cluster
transitions and potential lineage replacements.
* Broad Applicability: Analyzes data from various pathogens, including influenza, HIV, and Dengue viruses.
It can be applied to any continuous and relational phenotype under directional selection pressure.
Methods are described in Arhami and Rohani (2025) <doi:10.1093/bioinformatics/btaf372>.

Omid Arhami

topolow

Antigenic Mapping and Antigenic Velocity Algorithm

increase_na_percentage function

<dl><dt>mat</dt>
<dd>Matrix to modify</dd>
<dt>target_na_percentage</dt>
<dd>Numeric between 0 and 1 specifying desired proportion of NAs</dd></dl>

Arguments

Increase Missing Values in a Matrix — increase_na_percentage

<dl>

<dt>mat</dt>
<dd>Matrix to modify</dd>


<dt>target_na_percentage</dt>
<dd>Numeric between 0 and 1 specifying desired proportion of NAs</dd>

</dl>

increase_na_percentage: Increase Missing Values in a Matrix

Description

Usage

Value

Arguments

Details

Examples