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Table (.dat)

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  • Import and Export fully support the tabular data format and provide various data conversion and formatting options.
  • Import automatically recognizes common number formats, including C and Fortran notations.
  • Numbers without decimal points are imported as integers.

Background & Context

    • Generic tabular data.
    • Stores numerical and textual information, formatted as a table.
    • Supports user-defined field and record separators, field delimiters, currency tokens, and number formats.
    • Plain text format.

Import & Export

  • Import["file.dat"] returns a list of lists containing strings and numbers representing the rows and columns stored in the file.
  • Import["file.dat",elem] imports the specified element from a Table file.
  • Import["file.dat",{elem,subelem1,…}] imports subelements subelemi, useful for partial data import.
  • Import["file.dat",{{elem1,elem2,…}}] imports multiple elements.
  • The import format can be specified with Import["file","Table"] or Import["file",{"Table",elem,…}].
  • Export["file.dat",expr] creates a Table file from expr.
  • Supported expressions expr include:
  • {v1,v2,…}a single column of data
    {{v11,v12,…},{v21,v22,…},…}lists of rows of data
    arrayan array such as SparseArray, QuantityArray, etc.
    tseriesa TimeSeries, EventSeries or a TemporalData object
    Dataset[…]a dataset
    Tabular[…]a tabular object
  • See the following reference pages for full general information:
  • Import, Exportimport from or export to a file
    CloudImport, CloudExportimport from or export to a cloud object
    ImportString, ExportStringimport from or export to a string
    ImportByteArray, ExportByteArrayimport from or export to a byte array

Notebook Interface

  • Save Selection As exports the selected part of a notebook as a Table file.

Import Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Summary"summary of the file
    "Rules"list of rules for all available elements
  • Data representation elements:
  • "Data"two-dimensional array, representing the rows and columns
    "Grid"table data as a Grid object
    "Tabular"table data as a Tabular object
  • Import and Export use the "Data" element by default.

Options

  • Import and Export option:
  • "TextDelimiters"Automaticstring or list of strings used to delimit non-numeric fields
  • By default, Export delimits text fields containing the field separator with double-quote characters.
  • With an explicit setting of "TextDelimiters", Export always uses the specified string tokens to delimit text fields, effectively cycling through the list of delimiters.
  • With "TextDelimiters"->{"<",">"}, Export wraps text fields in angular brackets.
  • Double-quote characters delimiting text fields are not imported by default.
  • Import options:
  • CharacterEncoding"ISOLatin1"raw character encoding used in the file
    "CurrencyTokens"{{"$", "£", "¥", "€"}, {"c", "¢", "p", "F"}}currency units to be skipped when importing numerical values
    "DateStringFormat"Nonedate format, given as a DateString specification
    "FieldSeparators"{" ","∖t"}string tokens taken to separate columns
    "HeaderLines"0number of lines to skip at the beginning of the file
    "IgnoreEmptyLines"Falsewhether to ignore empty lines
    "LineSeparators"{"∖r\n","∖n","\r"}string tokens taken to separate rows
    "NumberPoint""."decimal point string
    "NumberSigns"{"-","+"}strings to use for signs of negative and positive numbers
    "Numeric"Truewhether to import data fields as numbers if possible
    "RepeatedSeparators"Truewhether to parse a sequence of field separators as a single separator
  • With CharacterEncoding -> Automatic, Import attempts to infer the character encoding of the file.
  • Import converts table entries formatted as specified by the "DateStringFormat" option to a DateObject.
  • Empty lines and lines containing only whitespace characters are converted to an empty list by default. With "IgnoreEmptyLines" set to True, Import will skip empty lines.
  • With "Numeric"->False, numbers will be imported as strings in the form they appear in the file.
  • With the default setting for "LineSeparators", Import automatically recognizes all common conventions for the encoding of line-separator characters.
  • Export options:
  • AlignmentNonehow data is aligned within table columns
    CharacterEncoding"UTF8"raw character encoding used in the file
    "FieldSeparators""\t"string token used to separate columns
    "TableHeadings"Noneheadings for table columns and rows
  • Possible settings for Alignment are None, Left, Center, and Right.
  • "TableHeadings" can be set to the following values:
  • Noneno labels
    Automaticgives successive integer labels for columns and rows
    {"col1","col2",…}list of column labels
    {rhead,chead}specifies separate labels for the rows and columns
  • Export encodes line separator characters using the convention of the computer system on which the Wolfram Language is being run.

Examples

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Basic Examples  (4)Summary of the most common use cases

Import data from a Table file:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-x2uqj0

Import data as a Tabular object:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-hxwcms
Out[1]=1

Summary of a table file:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-jorcfv
Out[1]=1

Export an array of random numbers as a table:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-x9buno
Out[1]=1

Scope  (8)Survey of the scope of standard use cases

Import  (3)

Show all elements available in the file:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-4nwp2m
Out[1]=1

Import a tabular data file that uses vertical bars as field separators:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-5rwchx
Out[1]=1

Import converts dates to a Wolfram Language DateObject specification if the date format is specified:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-oo7jf0
Out[1]=1

Export  (5)

Create a UTF-8 encoded text file that contains currency tokens:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-zcpwf1
Out[1]=1

When importing this file, currency tokens are automatically skipped:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-hc81e4
Out[2]=2

The Wolfram Language automatically converts expressions to a list of lists when exporting to the Table format:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-qbwiw3
Out[1]=1
In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-4o88nx
Out[2]=2

Table export uses the CForm for Real values:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-o8m499
Out[1]=1

Export an array of random numbers as a table:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-u3pxf2
Out[1]=1

Export a table formatted as a grid:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-pp882j
Out[1]=1

Import the generated file:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-qfp16k
Out[2]=2

Use ExportString to create a formatted version of an array:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-ug5fnr
Out[3]=3

Import Elements  (5)

Data  (2)

Import data from a table file:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-i4lk3
Out[3]=3

This is also the default element:

In[4]:=4
✖
https://wolfram.com/xid/0knlu3m-y6nmcj
Out[4]=4

Create a text grid from data:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-l6fj3c
Out[1]=1

Grid  (1)

Import data from a table file as Grid:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-e1hmgo
Out[1]=1

Summary  (1)

Get the file summary:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-ovc7rt
Out[1]=1

Tabular  (1)

Get the data from a file as a Tabular object:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-cwhsjd
Out[1]=1

Import Options  (11)

CharacterEncoding  (1)

The character encoding can be set to any value from $CharacterEncodings:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-v2b17f
In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-6qz5o6
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-2rqfrh
Out[3]=3

"CurrencyTokens"  (1)

Currency tokens are automatically skipped:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-cfmerz
Out[1]=1

Use the "CurrencyTokens"->None to include all currency tokens:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-bu5xt
Out[3]=3

"DateStringFormat"  (1)

By default, no date conversion is happening:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-gd2biv
Out[2]=2

Convert dates to a DateObject using the date format specified:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-qtt0ch
Out[1]=1

"FieldSeparators"  (1)

By default, " " and "∖t" are used as a field separators:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-e3y45w
Out[2]=2

Use " | " as a field separator:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-isgxag
Out[3]=3

"HeaderLines"  (1)

Table files may include comment lines:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-gzwww2
Out[1]=1

Specify the number of comment lines to skip:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-ep05gk
Out[2]=2

"IgnoreEmptyLines"  (1)

Use "IgnoreEmptyLines" to remove lines with no data from the imported data:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-20tvba
In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-0mba7z
Out[3]=3
In[5]:=5
✖
https://wolfram.com/xid/0knlu3m-27gz8u
Out[5]=5

"LineSeparators"  (1)

Use "LineSeparators" to separate rows:

In[7]:=7
✖
https://wolfram.com/xid/0knlu3m-bivgfc
In[8]:=8
✖
https://wolfram.com/xid/0knlu3m-5znx7
Out[8]=8
In[9]:=9
✖
https://wolfram.com/xid/0knlu3m-b084r
Out[9]=9

"NumberPoint"  (1)

By default, "." is used to specify decimal point character for floating-point data:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-b1f6a0
Out[1]=1
In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-buv0yl
Out[2]=2

Use "NumberPoint" option to specify decimal point character for floating-point data:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-k1nx6
Out[3]=3
In[4]:=4
✖
https://wolfram.com/xid/0knlu3m-k8y5ko
Out[4]=4

"NumberSigns"  (1)

By default, "-" and "+" are used for signs of negative and positive numbers:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-b9u9w1
Out[1]=1

Use "NumberSigns" option to specify signs of negative and positive numbers:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-e3y1jp
Out[2]=2

"Numeric"  (1)

By default, Import interprets numbers:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-l7d90a

Use "Numeric"->False to import everything as strings:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-kko935

"RepeatedSeparators"  (1)

By default, a sequence of field separators is parsed as a single separator:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-u4uee
In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-d0ra6z
Out[2]=2

Use "RepeatedSeparators"->False to disable that behavior:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-fnmkdk
Out[3]=3

Export Options  (4)

Alignment  (1)

By default, no additional characters are added for any alignment:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-b5pn1e
Out[1]=1

Left-align column values:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-062g9q
Out[2]=2

Center-align column values:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-t3aeaj
Out[3]=3

CharacterEncoding  (1)

The character encoding can be set to any value from $CharacterEncodings:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-q6fnby
In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-kukx8w
Out[2]=2
In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-b5ifl
Out[3]=3

"FieldSeparators"  (1)

By default, "\t" is used to separate columns:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-77t37
Out[1]=1

Use "FieldSeparators" option to specify a different separator:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-dhdd39
Out[2]=2

"TableHeadings"  (1)

Export data using custom column headers:

In[1]:=1
✖
https://wolfram.com/xid/0knlu3m-895ej8
Out[1]=1

Export data using custom column and row headers:

In[2]:=2
✖
https://wolfram.com/xid/0knlu3m-69ahdp
Out[2]=2

Export data using successive integer labels for columns and rows:

In[3]:=3
✖
https://wolfram.com/xid/0knlu3m-g8j3xu
Out[3]=3