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Returns a lookup table that maps a Tensor
of indices into strings.
tf.contrib.lookup.index_to_string_table_from_file(
vocabulary_file, vocab_size=None, default_value='UNK', name=None,
key_column_index=TextFileIndex.LINE_NUMBER,
value_column_index=TextFileIndex.WHOLE_LINE, delimiter='\t'
)
This operation constructs a lookup table to map int64 indices into string
values. The table is initialized from a vocabulary file specified in
vocabulary_file
, where the whole line is the value and the
zero-based line number is the index.
Any input which does not have a corresponding index in the vocabulary file
(an out-of-vocabulary entry) is assigned the default_value
The underlying table must be initialized by calling
session.run(tf.compat.v1.tables_initializer())
or
session.run(table.init())
once.
To specify multi-column vocabulary files, use key_column_index and value_column_index and delimiter.
- TextFileIndex.LINE_NUMBER means use the line number starting from zero, expects data type int64.
- TextFileIndex.WHOLE_LINE means use the whole line content, expects data type string.
- A value >=0 means use the index (starting at zero) of the split line based
on
delimiter
.
Sample Usages:
If we have a vocabulary file "test.txt" with the following content:
emerson
lake
palmer
indices = tf.constant([1, 5], tf.int64)
table = tf.lookup.index_to_string_table_from_file(
vocabulary_file="test.txt", default_value="UNKNOWN")
values = table.lookup(indices)
...
tf.compat.v1.tables_initializer().run()
values.eval() ==> ["lake", "UNKNOWN"]
Args | |
---|---|
vocabulary_file
|
The vocabulary filename, may be a constant scalar Tensor .
|
vocab_size
|
Number of the elements in the vocabulary, if known. |
default_value
|
The value to use for out-of-vocabulary indices. |
name
|
A name for this op (optional). |
key_column_index
|
The column index from the text file to get the key
values from. The default is to use the line number, starting from zero.
|
value_column_index
|
The column index from the text file to get the value
values from. The default is to use the whole line content.
|
delimiter
|
The delimiter to separate fields in a line. |
Returns | |
---|---|
The lookup table to map a string values associated to a given index int64
Tensors .
|
Raises | |
---|---|
ValueError
|
when vocabulary_file is empty.
|
ValueError
|
when vocab_size is invalid.
|