Apertium stream format

En français

This page describes the stream format used in the Apertium machine translation platform.

Characters

Reserved

Reserved characters should only appear escaped in the input stream unless they are part of a lexical unit, chunk or superblank.

• The characters ^ and $ are reserved for delimiting lexical units
• The character / is reserved for delimiting analyses in ambiguous lexical units
• The characters < and > are reserved for encapsulating tags
• The characters { and } are reserved for delimiting chunks
• The character \ is the escape character

Special

• Asterisk, '*' -- Unanalysed word.
• At sign, '@' -- Untranslated lemma.
• Hash sign, '#'
  • In morphological generation -- Unable to generate surface form from lexical unit.
  • In morphological analysis -- Start of invariable part of multiword marker.
• Plus symbol, '+' -- Joined lexical units
• Tilde '~' -- Word needs treating by post-generator.

Python parsing library

If you're writing a python script that needs to handle the Apertium stream format, try the excellent https://github.com/apertium/streamparser which lets you do "for lu in parse(file): analyses=lu.readings" etc. without having to worry about superblanks and escaped characters and such :-)

Formatted input

See also: Format handling

F = formatted text, T = text to be analysed.

Formatted text is treated as a single whitespace by all stages.

[<em>]this is[<\/em> ]a[ <b>]test.[][<\/b>]

|____|       |_______| |____|     |_______|
   |            |        |            |
   F            F        F            F
    
[<em>]this is[<\/em> ]a[ <b>]test.[][<\/b>]
      |______|        |      |____|
          |           |        | 
          T           T        T

Analyses

S = surface form, L = lemma.

^vino/vino<n><m><sg>/venir<vblex><ifi><p3><sg>$

   |    | |________|
   S    L    TAGS
        |______|
        ANALISIS

|_____________________________________________|
          AMBIGUOUS LEXICAL UNIT

^vino<n><m><sg>$

|______________|
 DISAMBIGUATED
  LEXICAL UNIT

^dímelo/decir<vblex><imp><p2><sg>+me<prn><enc><p1><mf><sg>+lo<prn><enc><p3><nt>/decir<vblex><imp><p2><sg>+me<prn><enc><p1><mf><sg>+lo<prn><enc><p3><m><sg>$

                                 |____________________________________________|
                                                JOINED MORPHEMES

^take it away/take<vblex><sep><inf>+prpers<prn><obj><p3><nt><sg># away/take<vblex><sep><pres>+prpers<prn><obj><p3><nt><sg># away$

              |___|                                             |_____|
                |                                                   |
             LEMMA HEAD                                        LEMMA QUEUE

Chunks

See also: Chunking

^Verbcj<SV><vblex><ifi><p3><sg>{^come<vblex><ifi><p3><sg>$}$ ^pr<PREP>{^to<pr>$}$ ^det_nom<SN><f><sg>{^the<det><def><3>$ ^beach<n><3>$}$

   |   |______________________||__________________________|                                                          |
 CHUNK      CHUNK TAGS              LEXICAL UNITS IN                                                               LINKED
  NAME                                  THE CHUNK                                                                   TAG

   |________________________________________|
                       |
                     CHUNK



^det_nom<SN><f><sg>{^the<det><def><3>$ ^beach<n><3>$}$

                                   |______________|
                                          |
                                POINTERS TO CHUNK TAGS
        <1> <2> <3>     

See also

• List of symbols
• Meaning of symbols * @ and dieze after a translation
• apertium-cleanstream which lets you avoid ad-hoc bash oneliners to get one word per line