# TOMsimilarity: Topological overlap matrix similarity and dissimilarity In WGCNA: Weighted Correlation Network Analysis

 TOMsimilarity R Documentation

## Topological overlap matrix similarity and dissimilarity

### Description

Calculation of the topological overlap matrix, and the corresponding dissimilarity, from a given adjacency matrix.

### Usage

```TOMsimilarity(
TOMType = "unsigned",
TOMDenom = "min",
suppressNegativeTOM = FALSE,
useInternalMatrixAlgebra = FALSE,
verbose = 1,
indent = 0)
TOMdist(
TOMType = "unsigned",
TOMDenom = "min",
suppressNegativeTOM = FALSE,
useInternalMatrixAlgebra = FALSE,
verbose = 1,
indent = 0)
```

### Arguments

 `adjMat` adjacency matrix, that is a square, symmetric matrix with entries between 0 and 1 (negative values are allowed if `TOMType=="signed"`). `TOMType` one of `"none"`, `"unsigned"`, `"signed"`, `"signed Nowick"`, `"unsigned 2"`, `"signed 2"` and `"signed Nowick 2"`. If `"none"`, adjacency will be used for clustering. See `TOMsimilarityFromExpr` for details. `TOMDenom` a character string specifying the TOM variant to be used. Recognized values are `"min"` giving the standard TOM described in Zhang and Horvath (2005), and `"mean"` in which the `min` function in the denominator is replaced by `mean`. The `"mean"` may produce better results but at this time should be considered experimental.
 `suppressTOMForZeroAdjacencies` Logical: should the results be set to zero for zero adjacencies? `suppressNegativeTOM` Logical: should the result be set to zero when negative? `useInternalMatrixAlgebra` Logical: should WGCNA's own, slow, matrix multiplication be used instead of R-wide BLAS? Only useful for debugging. `verbose` integer level of verbosity. Zero means silent, higher values make the output progressively more and more verbose. `indent` indentation for diagnostic messages. Zero means no indentation, each unit adds two spaces.

### Details

The functions perform basically the same calculations of topological overlap. `TOMdist` turns the overlap (which is a measure of similarity) into a measure of dissimilarity by subtracting it from 1.

Basic checks on the adjacency matrix are performed and missing entries are replaced by zeros.

See `TOMsimilarityFromExpr` for details on the various TOM types.

The underlying C code assumes that the diagonal of the adjacency matrix equals 1. If this is not the case, the diagonal of the input is set to 1 before the calculation begins.

### Value

A matrix holding the topological overlap.

Peter Langfelder

### References

Bin Zhang and Steve Horvath (2005) "A General Framework for Weighted Gene Co-Expression Network Analysis", Statistical Applications in Genetics and Molecular Biology: Vol. 4: No. 1, Article 17

For the Nowick-type signed TOM (referred to as weighted TO, wTO, by Nowick et al.), see

Nowick K, Gernat T, Almaas E, Stubbs L. Differences in human and chimpanzee gene expression patterns define an evolving network of transcription factors in brain. Proc Natl Acad Sci U S A. 2009 Dec 29;106(52):22358-63. doi: 10.1073/pnas.0911376106. Epub 2009 Dec 10.

or Gysi DM, Voigt A, Fragoso TM, Almaas E, Nowick K. wTO: an R package for computing weighted topological overlap and a consensus network with integrated visualization tool. BMC Bioinformatics. 2018 Oct 24;19(1):392. doi: 10.1186/s12859-018-2351-7.

`TOMsimilarityFromExpr`