Read a tree from TNT's parenthetical output.

ReadTntTree(filepath, relativePath = NULL, keepEnd = 1L, tipLabels = NULL)

TntText2Tree(treeText)

TNTText2Tree(treeText)

## Arguments

filepath

character string specifying path to TNT .tre file, relative to the R working directory (visible with getwd()).

relativePath

(discouraged) character string specifying location of the matrix file used to generate the TNT results, relative to the current working directory. Taxon names will be read from this file if they are not specified by tipLabels.

keepEnd

(optional, default 1) integer specifying how many elements of the file path to conserve when creating relative path (see examples).

tipLabels

(optional) character vector specifying the names of the taxa, in the sequence that they appear in the TNT file. If not specified, taxon names will be loaded from the data file linked in the first line of the .tre file specified in filepath.

treeText

Character string describing one or more trees, in the parenthetical format output by TNT.

## Value

ReadTntTree() returns a tree of class phylo, corresponding to the tree in filepath, or NULL if no trees are found.

## Details

TNT is software for parsimony analysis. Whilst its implementation of tree search is extremely rapid, analysis of results in TNT is made difficult by its esoteric and scantly documented scripting language.

ReadTntTree() aims to aid the user by facilitating the import of trees generated in TNT into R for further analysis.

The function depends on tree files being saved by TNT in parenthetical notation, using the TNT command tsav*. Trees are easiest to load into R if taxa have been saved using their names (TNT command taxname=). In this case, the TNT .tre file contains tip labels and can be parsed directly. The downside is that the uncompressed .tre files will have a larger file size.

ReadTntTree() can also read .tre files in which taxa have been saved using their numbers (taxname-). Such files contain a hard-coded link to the matrix file that was used to generate the trees, in the first line of the .tre file. This poses problems for portability: if the matrix file is moved, or the .tre file is accessed on another computer, the taxon names may be lost. As such, it is important to check that the matrix file exists in the expected location -- if it does not, either use the relativePath argument to point to its new location, or specify tipLabels to manually specify the tip labels.

TntText2Tree() converts text representation of a tree in TNT to an object of class phylo.

## Author

Martin R. Smith (martin.smith@durham.ac.uk)

## Examples

# In the examples below, TNT has read a matrix from
# "c:/TreeTools/input/dataset.nex"
# The results of an analysis were written to
# "c:/TreeTools/output/results1.tnt"
#
# results1.tnt will contain a hard-coded reference to
# "c:/TreeTools/input/dataset.nex".

# On the original machine (but not elsewhere), it would be possible to read
# this hard-coded reference from results.tnt:

# These datasets are provided with the "TreeTools" package, which will
# probably not be located at c:/TreeTools on your machine:

oldWD <- getwd() # Remember the current working directory
setwd(system.file(package = "TreeTools"))

# If taxon names were saved within the file (using taxname= in TNT),
# then our job is easy:
#>
#> Phylogenetic tree with 5 tips and 4 internal nodes.
#>
#> Tip labels:
#>   taxon_a, taxon_b, taxon_c, taxon_d, taxon_e
#>
#> Rooted; no branch lengths.

# But if taxa were compressed to numbers (using taxname-), we need to
# look up the original matrix in order to dereference the tip names.
#
# We need to extract the relevant file path from the end of the
# hard-coded path in the original file.
#
# We are interested in the last two elements of
# c:/TreeTools/input/dataset.nex
#                2      1
#
# "." means "relative to the current directory"
#> 2 phylogenetic trees

# If working in a lower subdirectory
setwd("./extdata/otherfolder")

# then it will be necessary to navigate up the directory path with "..":
#> 2 phylogenetic trees

setwd(oldWD) # Restore original working directory

TNTText2Tree("(A (B (C (D E ))));")
#>
#> Phylogenetic tree with 5 tips and 4 internal nodes.
#>
#> Tip labels:
#>   A, B, C, D, E
#>
#> Rooted; no branch lengths.