R: Return melted data for each token in a whitespace-separated...

melt_table {readr} | R Documentation

## Return melted data for each token in a whitespace-separated file

### Description

For certain non-rectangular data formats, it can be useful to parse the data into a melted format where each row represents a single token.

`melt_table()` and `melt_table2()` are designed to read the type of textual data where each column is separated by one (or more) columns of space.

`melt_table2()` allows any number of whitespace characters between columns, and the lines can be of different lengths.

`melt_table()` is more strict, each line must be the same length, and each field is in the same position in every line. It first finds empty columns and then parses like a fixed width file.

### Usage

    melt_table(
      file,
      locale = default_locale(),
      na = "NA",
      skip = 0,
      n_max = Inf,
      guess_max = min(n_max, 1000),
      progress = show_progress(),
      comment = "",
      skip_empty_rows = FALSE
    )

    melt_table2(
      file,
      locale = default_locale(),
      na = "NA",
      skip = 0,
      n_max = Inf,
      progress = show_progress(),
      comment = "",
      skip_empty_rows = FALSE
    )

### Arguments

`file` | Either a path to a file, a connection, or literal data (either a single string or a raw vector). Files ending in `.gz`, `.bz2`, `.xz`, or `.zip` will be automatically uncompressed. Files starting with `http://`, `https://`, `ftp://`, or `ftps://` will be automatically downloaded. Remote gz files can also be automatically downloaded and decompressed. Literal data is most useful for examples and tests. It must contain at least one new line to be recognised as data (instead of a path) or be a vector of greater than length 1. Using a value of `clipboard()` will read from the system clipboard.
`locale` | The locale controls defaults that vary from place to place. The default locale is US-centric (like R), but you can use `locale()` to create your own locale that controls things like the default time zone, encoding, decimal mark, big mark, and day/month names.
`na` | Character vector of strings to interpret as missing values. Set this option to `character()` to indicate no missing values.
`skip` | Number of lines to skip before reading data.
`n_max` | Maximum number of records to read.
`guess_max` | Maximum number of records to use for guessing column types.
`progress` | Display a progress bar? By default it will only display in an interactive session and not while knitting a document. The display is updated every 50,000 values and will only display if estimated reading time is 5 seconds or more. The automatic progress bar can be disabled by setting option `readr.show_progress` to `FALSE`.
`comment` | A string used to identify comments. Any text after the comment characters will be silently ignored.
`skip_empty_rows` | Should blank rows be ignored altogether? i.e. If this option is `TRUE` then blank rows will not be represented at all. If it is `FALSE` then they will be represented by `NA` values in all the columns.

### See Also

`melt_fwf()` to melt fixed width files where each column is not separated by whitespace. `melt_fwf()` is also useful for reading tabular data with non-standard formatting. `read_table()` is the conventional way to read tabular data from whitespace-separated files.

### Examples

    # One corner from http://www.masseyratings.com/cf/compare.htm
    massey <- readr_example("massey-rating.txt")
    cat(read_file(massey))
    melt_table(massey)

    # Sample of 1978 fuel economy data from
    # http://www.fueleconomy.gov/feg/epadata/78data.zip
    epa <- readr_example("epa78.txt")
    cat(read_file(epa))
    melt_table(epa)

[Package readr version 1.4.0 Index]