align.test {word.alignment}

Computing One-to-Many Word Alignment Using a Parallel Corpus for a Given Test Set

Description

For a given parallel corpus based on IBM Model 1, it aligns the words of a given sentence-aligned test set.

Usage

align.test(file.sorc, file.trgt, test.sorc, test.trgt, 
           n.train = -1, n.test = -1, minlen.train = 5, maxlen.train = 40, 
           minlen.test = 5, maxlen.test = 40, null.tokens = TRUE, 
           dtfile.path = NULL, file.align = 'alignment',
           name.sorc='f',name.trgt='e',iter = 3, ...)

Arguments

file.sorc

the name of source language file in training set.

file.trgt

the name of target language file in training set.

test.sorc

the name of source language file in test set.

test.trgt

the name of target language file in test set.

n.train

the number of sentences in the training set to be read. If -1, it considers all sentences.

n.test

the number of sentences in the test set to be read. If -1, it considers all sentences.

minlen.train

a minimum length of sentences in training set.

maxlen.train

a maximum length of sentences in training set.

minlen.test

a minimum length of sentences in test set.

maxlen.test

a maximum length of sentences in test set.

null.tokens

logical. If TRUE, "null" is added at the first of each source sentence of the test set.

dtfile.path

if NULL (usually for the first time), a data.table will be created contaning cross words of all sentences with their matched probabilities. It saves into a file named as a combination of name.sorc, name.trgt, n and iter as "f.e.n.iter.RData".

If specific file name is set, it will be read and continue the rest of the function, i.e. : finding the word alignments for the test set.

file.align

the output results file name.

name.sorc

it is a notation for the source language (default = 'f').

name.trgt

it is a notation for the target language (default = 'e').

iter

the number of iterations for IBM Model 1.

...

Further arguments to be passed to prepare.data.

Details

If dtfile.path = NULL, the following question will be asked:

"Are you sure that you want to run the align.ibm1 function (It takes time)? (Yes/ No: if you want to specify word alignment path, please press 'No'.)

Value

an RData object as "file.align.n.iter.Rdata".

Note

Note that we have a memory restriction and so just special computers with a high CPU and a big RAM can allocate the vectors of this function. Of course, it depends on the corpus size.

Author(s)

Neda Daneshgar and Majid Sarmad.

References

Koehn P. (2010), "Statistical Machine Translation.", Cambridge University, New York.

Lopez A. (2008), "Statistical Machine Translation.", ACM Computing Surveys, 40(3).

Peter F., Brown J. (1990), "A Statistical Approach to Machine Translation.", Computational Linguistics, 16(2), 79-85.

Supreme Council of Information and Communication Technology. (2013), Mizan English-Persian Parallel Corpus. Tehran, I.R. Iran. Retrieved from http://dadegan.ir/catalog/mizan.

http://statmt.org/europarl/v7/bg-en.tgz

See Also

align.ibm1, evaluation, scan

Examples

# Since the extraction of  bg-en.tgz in Europarl corpus is time consuming, 
# so the aforementioned unzip files have been temporarily exported to 
# http://www.um.ac.ir/~sarmad/... .
# In addition, in this example we use the first five sentence pairs of training set as the 
# test set.
## Not run: 

ats = align.test ('http://www.um.ac.ir/~sarmad/word.a/euro.bg',
                      'http://www.um.ac.ir/~sarmad/word.a/euro.en',  
                      'http://www.um.ac.ir/~sarmad/word.a/euro.bg',
                      'http://www.um.ac.ir/~sarmad/word.a/euro.en',
                       n.train = 100,n.test = 5, encode.sorc = 'UTF-8')               

## End(Not run)