[Superseded] This function has been superseded in readr and moved to the meltr package.

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.

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. To be recognised as literal data, the input must be either wrapped with I(), be a string containing at least one new line, or be a vector containing at least one string with a new line.

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 lines to read.

guess_max

Maximum number of lines 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 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))
#> UCC PAY LAZ KPK  RT   COF BIH DII ENG ACU Rank Team            Conf
#>   1   1   1   1   1     1   1   1   1   1    1 Ohio St          B10 
#>   2   2   2   2   2     2   2   2   4   2    2 Oregon           P12 
#>   3   4   3   4   3     4   3   4   2   3    3 Alabama          SEC 
#>   4   3   4   3   4     3   5   3   3   4    4 TCU              B12 
#>   6   6   6   5   5     7   6   5   6  11    5 Michigan St      B10 
#>   7   7   7   6   7     6  11   8   7   8    6 Georgia          SEC 
#>   5   5   5   7   6     8   4   6   5   5    7 Florida St       ACC 
#>   8   8   9   9  10     5   7   7  10   7    8 Baylor           B12 
#>   9  11   8  13  11    11  12   9  14   9    9 Georgia Tech     ACC 
#>  13  10  13  11   8     9  10  11   9  10   10 Mississippi      SEC 
melt_table(massey)
#> Warning: `melt_table()` was deprecated in readr 2.0.0.
#> Please use `meltr::melt_table()` instead
#> # A tibble: 143 × 4
#>      row   col data_type value
#>    <dbl> <dbl> <chr>     <chr>
#>  1     1     1 character UCC  
#>  2     1     2 character PAY  
#>  3     1     3 character LAZ  
#>  4     1     4 character KPK  
#>  5     1     5 character RT   
#>  6     1     6 character COF  
#>  7     1     7 character BIH  
#>  8     1     8 character DII  
#>  9     1     9 character ENG  
#> 10     1    10 character ACU  
#> # … with 133 more rows

# Sample of 1978 fuel economy data from
# http://www.fueleconomy.gov/feg/epadata/78data.zip
epa <- readr_example("epa78.txt")
cat(read_file(epa))
#> ALFA ROMEO                                                                     ALFA ROMEO           78010003
#> ALFETTA                              03  81  8    74  7   89  9                ALFETTA              78010053
#> SPIDER 2000                          01                                        SPIDER 2000          78010103
#> AMC                                                                            AMC                  78020002
#> GREMLIN                              03  79  9                    79  9        GREMLIN              78020053
#> PACER                                04  89 11                    89 11        PACER                78020103
#> PACER WAGON                          07  90 26    91 26                        PACER WAGON          78020153
#> CONCORD                              04  88 12    90 11   90 11   83 16        CONCORD              78020203
#> CONCORD WAGON                        07  91 30            91 30                CONCORD WAGON        78020253
#> MATADOR COUPE                        05  97 14    97 14                        MATADOR COUPE        78020303
#> MATADOR SEDAN                        06 110 20           110 20                MATADOR SEDAN        78020353
#> MATADOR WAGON                        09 112 50           112 50                MATADOR WAGON        78020403
#> ASTON MARTIN                                                                   ASTON MARTIN         78040002
#> ASTON MARTIN                                                                   ASTON MARTIN         78040053
#> AUDI                                                                           AUDI                 78050002
#> FOX                                  03  84 11    84 11   84 11                FOX                  78050053
#> FOX WAGON                            07  83 40            83 40                FOX WAGON            78050103
#> 5000                                 04  90 15            90 15                5000                 78050153
#> AVANTI                                                                         AVANTI               78065002
#> AVANTI II                            02  75  8    75  8                        AVANTI II            78065053
melt_table(epa)
#> Warning: `melt_table()` was deprecated in readr 2.0.0.
#> Please use `meltr::melt_table()` instead
#> # A tibble: 240 × 4
#>      row   col data_type value       
#>    <dbl> <dbl> <chr>     <chr>       
#>  1     1     1 character "ALFA ROMEO"
#>  2     1     2 empty     ""          
#>  3     1     3 empty     ""          
#>  4     1     4 empty     ""          
#>  5     1     5 empty     ""          
#>  6     1     6 empty     ""          
#>  7     1     7 empty     ""          
#>  8     1     8 empty     ""          
#>  9     1     9 empty     ""          
#> 10     1    10 empty     ""          
#> # … with 230 more rows