List

  • Import and Export provide various data conversion and formatting options for storing lists of numbers or strings.
  • Import automatically recognizes common number formats, including C and Fortran notations.
  • Numbers without decimal points are imported as integers.

BackgroundBackground

    Column of numbers or strings.
    Stores a list of numbers or strings as lines.
    Plain text format.
    Is essentially a single-column version of the "Table" format.

Import and ExportImport and Export

  • Import["file","List"] imports a text file, returning each line as a string or a number.
  • Export["file",list,"List"] writes any list as a column of numbers or strings.
  • Import["file","List"] returns a list of strings or numbers, each representing a line of file.
  • Export["file",list,"List"] exports list as a column, writing the CForm of each element as a separate line.
  • Import["file",{"List",elem} ] imports the specified element from a file.
  • Import["file",{"List",elem,suba,subb,}] imports a subelement.
  • Import["file",{"List",{elem1,elem2,}}] imports multiple elements.
  • The format must be explicitly given.
  • Export["file",expr, {"List",elem}] creates a file by treating expr as specifying element elem.
  • Export["file",{expr1,expr2,},{"List",{elem1,elem2,}}] treats each as specifying the corresponding .
  • Export["file",expr,"List",opt1->val1,] exports expr with the specified option elements taken to have the specified values.
  • Export["file",{elem1->expr1,elem2->expr2,},{"List","Rules"}] uses rules to specify the elements to be exported.
  • See the reference pages for full general information on Import and Export.
  • ImportString and ExportString support the format.

ElementsElements

  • General Import elements:
  • "Elements"list of elements and options available in this file
    "Rules"full list of rules for each element and option
    "Options"list of rules for options, properties, and settings
  • Data representation elements:
  • "Data"list of numbers or strings, each representing a line
    "Grid"list data as a Grid object
  • Import and Export use the element by default.

OptionsOptions

  • General Export options:
  • AlignmentNonehow data is aligned within table columns
    CharacterEncoding"UTF8"raw character encoding used in the file
  • Possible settings for Alignment are None, Left, Center, and Right.
  • General Import option:
  • CharacterEncoding"ASCII"raw character encoding used in the file
  • Import and Export option:
  • "EmptyField"""how to represent empty fields
  • Import options:
  • "CurrencyTokens"{{"$", "£", "¥", "€"}, {"c", "¢", "p", "F"}}currency units to be skipped when importing numerical values
    "DateStringFormat"Nonedate format, given as a DateString specification
    "IgnoreEmptyLines"Falsewhether to ignore empty lines
    "LineSeparators"{"r\n","n","\r"}string tokens taken to separate list elements
    "Numeric"Truewhether to import data fields as numbers if possible
    "NumberPoint""."string to use for a decimal point
    "NumberSigns"{"-","+"}strings to use for signs of negative and positive numbers
    "HeaderLines"0number of lines to skip at the beginning of the file
  • Import converts table entries formatted as specified by the option to a DateList representation of the form .
  • Empty lines and lines containing only whitespace characters are converted to an empty string by default. With 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.
  • All common conventions for the encoding of newline characters are recognized with the default setting of .

ExamplesExamplesopen allclose all

Basic Examples  (4)Basic Examples  (4)

Import a text file as a list of strings:

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Import converts records to integers or reals if possible:

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Currency symbols are automatically omitted when importing as a list:

In[1]:=
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Export a list of numbers using the format:

In[1]:=
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Introduced in 1999
(4.0)
| Updated in 2012
(9.0)