nvidia.dali.fn.lookup_table¶
-
nvidia.dali.fn.
lookup_table
(*inputs, **kwargs)¶ Maps the input to output by using a lookup table that is specified by
keys
andvalues
, and adefault_value
for unspecified keys.For example when
keys
andvalues
are used to define the lookup table in the following way:keys[] = {0, 2, 3, 4, 5, 3} values[] = {0.2, 0.4, 0.5, 0.6, 0.7, 0.10} default_value = 0.99 0 <= i < max(keys) lut[i] = values[keys.index[i]] if i in keys lut[i] = default_value otherwise
the operator creates the following table:
lut[] = {0.2, 0.99, 0.4, 0.10, 0.6, 0.7} // only last occurrence of a key is considered
and produces the output according to this formula:
Output[i] = lut[Input[i]] if 0 <= Input[i] <= len(lut) Output[i] = default_value otherwise
Here is a practical example, considering the table defined above:
Input[] = {1, 4, 1, 0, 100, 2, 3, 4} Output[] = {0.99, 0.6, 0.99, 0.2, 0.99, 0.4, 0.10, 0.6}
Note
Only integer types can be used as inputs for this operator.
This operator allows sequence inputs and supports volumetric data.
- Supported backends
‘cpu’
‘gpu’
- Parameters
input (TensorList) – Input to the operator.
- Keyword Arguments
bytes_per_sample_hint (int or list of int, optional, default = [0]) –
Output size hint, in bytes per sample.
If specified, the operator’s outputs residing in GPU or page-locked host memory will be preallocated to accommodate a batch of samples of this size.
default_value (float, optional, default = 0.0) – Default output value for keys that are not present in the table.
dtype (nvidia.dali.types.DALIDataType, optional, default = DALIDataType.FLOAT) – Output data type.
keys (int or list of int, optional, default = []) –
A list of input values (keys) in the lookup table.
The length of
keys
andvalues
argument must match. The values inkeys
should be in the [0, 65535 ] range.preserve (bool, optional, default = False) – Prevents the operator from being removed from the graph even if its outputs are not used.
seed (int, optional, default = -1) –
Random seed.
If not provided, it will be populated based on the global seed of the pipeline.
values (float or list of float, optional, default = []) –
A list of mapped output
values
for eachkeys
entry.The length of the
keys
and thevalues
argument must match.output_dtype (nvidia.dali.types.DALIDataType) –
Warning
The argument
output_dtype
is a deprecated alias fordtype
. Usedtype
instead.