geva.merge.input {geva} | R Documentation

## GEVA Input Processing and Merge

### Description

Functions to read, load, and concatenate the experimental comparisons from the data input. This is the initial step to proceed with any GEVA analysis.

### Usage

    geva.merge.input(
      ...,
      col.values = "logFC",
      col.pvals = "adj.P.Val",
      col.other = NULL
    )

    geva.read.tables(
      filenames = NULL,
      dirname = ".",
      col.values = "logFC",
      col.pvals = "adj.P.Val",
      col.other = NULL,
      ...,
      files.pattern = "\\.txt$",
      p.value.cutoff = 0.05,
      read.args = list()
    )

### Arguments

`...` | multiple `matrix` or `data.frame` objects. At least two arguments are required for `geva.merge.input`, but it's optional for `geva.read.tables`. The optional arguments in `geva.read.tables` are also passed to its internal call to `geva.merge.input` and `geva.input.filter`. In addition, the following optional arguments are accepted: `na.val` : (`numeric`) value between `0` and `1` used as replacement when a p-value column is not present (default is `NA`) `use.regex` : (`logical`) whether to match the column names using regular expressions (default is `FALSE`) `verbose` : (`logical`) whether to print the current loading and merge progress (default is `TRUE`)
`col.values` | `character` vector, possible name(s) to match the logFC column(s) from each table
`col.pvals` | `character` vector, possible name(s) to match the p-value column(s) from each table
`col.other` | `character` vector, name(s) to match additional columns (e.g., gene symbols). Ignored if `NULL`
`filenames` | `character` vector with two or more file paths
`dirname` | single `character`, base directory containing the input files. Ignored if `filenames` is specified
`files.pattern` | single `character`, pattern used to filter the files inside `dirname`. Ignored if `filenames` is specified
`p.value.cutoff` | `numeric` (`0` to `1`), initial p-value threshold. Rows entirely composed by p-values above this cutoff (i.e., no significant logFC) are removed after the final merge. Ignored if `NA` or `NULL`
`read.args` | `list` of additional arguments passed to utils::read.table

### Details

The `geva.merge.input` function takes multiple tables as arguments (e.g., `matrix` or `data.frame` objects), extracts the logFC columns from each table and merges them into a single `GEVAInput` dataset.

The column names are specified in the `col.values` and `col.pvals` arguments (`character`) and must correctly match the column names for logFC and p-value columns, respectively, in the inputs to be extracted. Multiple values for column names can also be specified as valid name possibilities if they differ among the tables.

The function `geva.merge.input` reads multiple tab-delimited text files containing, extracts the logFC columns from each table and merges into a single `GEVAInput` dataset.

### Value

A `GEVAInput` object

### Note

The inclusion of p-value columns is not technically required, but strongly recommended as they improve the statistical accuracy in the summarization steps. If the p-value (or adjusted p-value) columns are present, their values are converted to weights by applying `1 - pvalue` for each `pvalue` element, otherwise an optional `na.val` optional argument can specified as replacement to the absent values (default is `NA`). Weights are used to accomodate the central logFC values towards the most significant observations and penalize potential statistical innacuracies.

### Examples

    ### EXAMPLE 1
    ## geva.merge.input example with three randomly generated tables
    ## (For demonstration purposes only)

    # Number of rows
    n <- 10000

    # Random row (probe) names
    probnms <- sprintf("PROBE_%s", 1:n)

    # Random gene names (optional)
    genenms <- paste0(sprintf("GENE_%s", 1:n), LETTERS[1:n %% (length(LETTERS)+1)])

    # Random table 1
    dt1 <- data.frame(row.names=probnms,
                      logfc=(rnorm(n, 0, sd=2) * rnorm(n, 0, sd=0.5)),
                      pvalues = runif(n, max=0.08),
                      genesymbol = genenms)
    # Random table 2
    dt2 <- data.frame(row.names=probnms,
                      logfc=(rnorm(n, 0, sd=2) * rnorm(n, 0, sd=0.5)),
                      pvalues = runif(n, max=0.08),
                      genesymbol = genenms)
    # Random table 3
    dt3 <- data.frame(row.names=probnms,
                      logfc=(rnorm(n, 0, sd=2) * rnorm(n, 0, sd=0.5)),
                      pvalues = runif(n, max=0.08),
                      genesymbol = genenms)

    # Merges the three tables
    ginput <- geva.merge.input(exp1=dt1, exp2=dt2, exp3=dt3,
                               col.values="logfc",
                               col.pvals="pvalues",
                               col.other="genesymbol")

    # Prints the first rows from the merged table
    print(head(ginput))               # values
    print(head(inputweights(ginput))) # weights

    # ---
    ## Not run:

    ### EXAMPLE 2
    ## geva.read.tables example with three tab-delimited files

    # Table file examples. Each one has 3 columns: "logfc", "pvalues", and "genesymbol"
    # Replace it with your tab-delimited files (e.g. exported from limma's topTable)
    fnames <- c("dt1.txt", "dt2.txt", "dt3.txt")

    ginput <- geva.read.tables(fnames,
                               col.values="logfc",
                               col.pvals="pvalues",
                               col.other="genesymbol")

    # Prints the first rows from the merged table
    print(head(ginput))               # values
    print(head(inputweights(ginput))) # weights

    # ---

    ### EXAMPLE 3
    ## geva.read.tables example with tab-delimited files in a directory

    # Directory name (replace it with a directory containing the table files)
    dirnm <- "C:/User/robertplant123/Documents/R/gevaexamples"

    # In this example, table files contain 3 columns: "logfc", "pvalues", and "genesymbol"
    # Reads all txt files in the directory
    ginput <- geva.read.tables(dirname=dirnm,
                               col.values="logfc",
                               col.pvals="pvalues",
                               col.other="genesymbol")

    # (Optional step)
    # Let's assume that all table file names start with "dt" and ends with the ".txt" extension,
    # such as dt1.txt, dt2.txt and so on...
    fname_pattern <- c("^dt.+?\\.txt$")  # Defines a RegEx pattern to find the files
    # Loads only files that match the file name pattern
    ginput <- geva.read.tables(dirname=dirnm,
                               files.pattern=fname_pattern,
                               col.values="logfc",
                               col.pvals="pvalues",
                               col.other="genesymbol")

    # Prints the first rows from the merged table
    print(head(ginput))               # values
    print(head(inputweights(ginput))) # weights

    ## End(Not run)

[Package geva version 1.2.0 Index]