90 lines
2.7 KiB
Markdown
90 lines
2.7 KiB
Markdown
Instance Batches
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================
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If you have to run experiments on multiple problem instances, *instance batches* are your friend. Simply put an instance batch is a collection of problem instances. In order to manage batches across large instance pools spread out over the file system you can declare them in *batch files*.
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Loading Batches
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---------------
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All you have to do in order to load a batch is to call the `batch.load("path/batch_file")` function with the path to the corresponding batch file.
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```python
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import a2.batch
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instance_paths = a2.batch.load("path/to/batch_file")
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```
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Batch Files
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-----------
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Batch files are used do index all instances contained in the batch. The real power of these files comes from two features *nested batches* and the possibility to *include batch files*. A example may look like this:
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```JSON
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{
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"dir": "./some/path",
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"include":
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[
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"path/to_other/batch_file1",
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"path/to_other/batch_file2"
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],
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"instances":
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[
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"instance1.cnf",
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"instance2.cnf"
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],
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"batches":
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[
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{
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"dir": "./nested/path",
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"instances":
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[
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"instanec11.cnf",
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"instance22.cnf"
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]
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}
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]
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}
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```
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A complete grammar is defined further below. The main components of a batch files are *batch objects*. Possible fields of batch objects are:
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dir
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: The base directory for all contained paths. Consider the example above. The path `instance1.cnf` will be expanded to `./some/path/instance1.cnf`.
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: If the base path of a batch is relative (e.g. `./path`) it is always relative to its parent batch (e.g. `./nested/path` will be extended to `./some/path/nested/path`). In case of root batches (highest level in batch file) relative base paths are relative to the file location.
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: If no `"dir:"` is specified, the base path of the parent batch is inherited (no `"dir:"` is similar to `"dir": "."`).
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include
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: Here you can list paths to other batch files, which than will be included to the current batch.
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instances
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: This is the actual list of instance paths.
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batches
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: Instance batches can contain other (nested) instance batches. This allows you to structure your batch files much more nicely (see nested base paths).
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---
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### Grammar
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The complete grammar of a batch file is defined by:
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```
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<file> ::= <batch>
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<batch> ::= '{' <fields> '}'
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<fields> ::= <field>
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| ',' <fields>
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<field> ::= <directory>
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| <instance list>
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| <include list>
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| <batch list>
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<directory> ::= '"dir":' <Path>
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<instance list> ::= '"instances": [' <paths> ']'
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<include list> ::= '"include": [' <paths> ']'
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<batch list> ::= '"batches": [' <batches> ']'
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<paths> ::= <path> | ',' <paths>
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<batches> ::= <batch> | ',' <batches>
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```
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---
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