spaCy/website/docs/usage/saving-loading.md

---
title: Saving and Loading
menu:
  - ['Basics', 'basics']
  - ['Serialization Methods', 'serialization-methods']
  - ['Entry Points', 'entry-points']
  - ['Models', 'models']
---

## Basics {#basics hidden="true"}

import Serialization101 from 'usage/101/\_serialization.md'

<Serialization101 />

<Infobox title="Important note" variant="warning">

In spaCy v2.0, the API for saving and loading has changed to only use the four
methods listed above consistently across objects and classes. For an overview of
the changes, see [this table](/usage/v2#incompat) and the notes on
[migrating](/usage/v2#migrating-saving-loading).

</Infobox>

### Serializing the pipeline {#pipeline}

When serializing the pipeline, keep in mind that this will only save out the
**binary data for the individual components** to allow spaCy to restore them –
not the entire objects. This is a good thing, because it makes serialization
safe. But it also means that you have to take care of storing the language name
and pipeline component names as well, and restoring them separately before you
can load in the data.

> #### Saving the model meta
>
> The `nlp.meta` attribute is a JSON-serializable dictionary and contains all
> model meta information, like the language and pipeline, but also author and
> license information.

```python
### Serialize
bytes_data = nlp.to_bytes()
lang = nlp.meta["lang"]  # "en"
pipeline = nlp.meta["pipeline"]  # ["tagger", "parser", "ner"]
```

```python
### Deserialize
nlp = spacy.blank(lang)
for pipe_name in pipeline:
    pipe = nlp.create_pipe(pipe_name)
    nlp.add_pipe(pipe)
nlp.from_bytes(bytes_data)
```

This is also how spaCy does it under the hood when loading a model: it loads the
model's `meta.json` containing the language and pipeline information,
initializes the language class, creates and adds the pipeline components and
_then_ loads in the binary data. You can read more about this process
[here](/usage/processing-pipelines#pipelines).

### Serializing Doc objects efficiently {#docs new="2.2"}

If you're working with lots of data, you'll probably need to pass analyses
between machines, either to use something like [Dask](https://dask.org) or
[Spark](https://spark.apache.org), or even just to save out work to disk. Often
it's sufficient to use the [`Doc.to_array`](/api/doc#to_array) functionality for
this, and just serialize the numpy arrays – but other times you want a more
general way to save and restore `Doc` objects.

The [`DocBin`](/api/docbin) class makes it easy to serialize and deserialize a
collection of `Doc` objects together, and is much more efficient than calling
[`Doc.to_bytes`](/api/doc#to_bytes) on each individual `Doc` object. You can
also control what data gets saved, and you can merge pallets together for easy
map/reduce-style processing.

```python
### {highlight="4,8,9,13,14"}
import spacy
from spacy.tokens import DocBin

doc_bin = DocBin(attrs=["LEMMA", "ENT_IOB", "ENT_TYPE"], store_user_data=True)
texts = ["Some text", "Lots of texts...", "..."]
nlp = spacy.load("en_core_web_sm")
for doc in nlp.pipe(texts):
    doc_bin.add(doc)
bytes_data = doc_bin.to_bytes()

# Deserialize later, e.g. in a new process
nlp = spacy.blank("en")
doc_bin = DocBin().from_bytes(bytes_data)
docs = list(doc_bin.get_docs(nlp.vocab))
```

If `store_user_data` is set to `True`, the `Doc.user_data` will be serialized as
well, which includes the values of
[extension attributes](/usage/processing-pipelines#custom-components-attributes) (if
they're serializable with msgpack).

<Infobox title="Important note on serializing extension attributes" variant="warning">

Including the `Doc.user_data` and extension attributes will only serialize the
**values** of the attributes. To restore the values and access them via the
`doc._.` property, you need to register the global attribute on the `Doc` again.

```python
docs = list(doc_bin.get_docs(nlp.vocab))
Doc.set_extension("my_custom_attr", default=None)
print([doc._.my_custom_attr for doc in docs])
```

</Infobox>

### Using Pickle {#pickle}

> #### Example
>
> ```python
> doc = nlp("This is a text.")
> data = pickle.dumps(doc)
> ```

When pickling spaCy's objects like the [`Doc`](/api/doc) or the
[`EntityRecognizer`](/api/entityrecognizer), keep in mind that they all require
the shared [`Vocab`](/api/vocab) (which includes the string to hash mappings,
label schemes and optional vectors). This means that their pickled
representations can become very large, especially if you have word vectors
loaded, because it won't only include the object itself, but also the entire
shared vocab it depends on.

If you need to pickle multiple objects, try to pickle them **together** instead
of separately. For instance, instead of pickling all pipeline components, pickle
the entire pipeline once. And instead of pickling several `Doc` objects
separately, pickle a list of `Doc` objects. Since the all share a reference to
the _same_ `Vocab` object, it will only be included once.

```python
### Pickling objects with shared data {highlight="8-9"}
doc1 = nlp("Hello world")
doc2 = nlp("This is a test")

doc1_data = pickle.dumps(doc1)
doc2_data = pickle.dumps(doc2)
print(len(doc1_data) + len(doc2_data))  # 6636116 😞

doc_data = pickle.dumps([doc1, doc2])
print(len(doc_data))  # 3319761 😃
```

<Infobox title="Pickling spans and tokens" variant="warning">

Pickling `Token` and `Span` objects isn't supported. They're only views of the
`Doc` and can't exist on their own. Pickling them would always mean pulling in
the parent document and its vocabulary, which has practically no advantage over
pickling the parent `Doc`.

```diff
- data = pickle.dumps(doc[10:20])
+ data = pickle.dumps(doc)
```

If you really only need a span – for example, a particular sentence – you can
use [`Span.as_doc`](/api/span#as_doc) to make a copy of it and convert it to a
`Doc` object. However, note that this will not let you recover contextual
information from _outside_ the span.

```diff
+ span_doc = doc[10:20].as_doc()
data = pickle.dumps(span_doc)
```

</Infobox>

## Implementing serialization methods {#serialization-methods}

When you call [`nlp.to_disk`](/api/language#to_disk),
[`nlp.from_disk`](/api/language#from_disk) or load a model package, spaCy will
iterate over the components in the pipeline, check if they expose a `to_disk` or
`from_disk` method and if so, call it with the path to the model directory plus
the string name of the component. For example, if you're calling
`nlp.to_disk("/path")`, the data for the named entity recognizer will be saved
in `/path/ner`.

If you're using custom pipeline components that depend on external data – for
example, model weights or terminology lists – you can take advantage of spaCy's
built-in component serialization by making your custom component expose its own
`to_disk` and `from_disk` or `to_bytes` and `from_bytes` methods. When an `nlp`
object with the component in its pipeline is saved or loaded, the component will
then be able to serialize and deserialize itself. The following example shows a
custom component that keeps arbitrary JSON-serializable data, allows the user to
add to that data and saves and loads the data to and from a JSON file.

> #### Real-world example
>
> To see custom serialization methods in action, check out the new
> [`EntityRuler`](/api/entityruler) component and its
> [source](https://github.com/explosion/spacy/tree/v2.x/spacy/pipeline/entityruler.py).
> Patterns added to the component will be saved to a `.jsonl` file if the
> pipeline is serialized to disk, and to a bytestring if the pipeline is
> serialized to bytes. This allows saving out a model with a rule-based entity
> recognizer and including all rules _with_ the model data.

```python
### {highlight="15-19,21-26"}
class CustomComponent(object):
    name = "my_component"

    def __init__(self):
        self.data = []

    def __call__(self, doc):
        # Do something to the doc here
        return doc

    def add(self, data):
        # Add something to the component's data
        self.data.append(data)

    def to_disk(self, path, **kwargs):
        # This will receive the directory path + /my_component
        data_path = path / "data.json"
        with data_path.open("w", encoding="utf8") as f:
            f.write(json.dumps(self.data))

    def from_disk(self, path, **cfg):
        # This will receive the directory path + /my_component
        data_path = path / "data.json"
        with data_path.open("r", encoding="utf8") as f:
            self.data = json.loads(f)
        return self
```

After adding the component to the pipeline and adding some data to it, we can
serialize the `nlp` object to a directory, which will call the custom
component's `to_disk` method.

```python
### {highlight="2-4"}
nlp = spacy.load("en_core_web_sm")
my_component = CustomComponent()
my_component.add({"hello": "world"})
nlp.add_pipe(my_component)
nlp.to_disk("/path/to/model")
```

The contents of the directory would then look like this.
`CustomComponent.to_disk` converted the data to a JSON string and saved it to a
file `data.json` in its subdirectory:

```yaml
### Directory structure {highlight="2-3"}
└── /path/to/model
    ├── my_component     # data serialized by "my_component"
    |   └── data.json
    ├── ner              # data for "ner" component
    ├── parser           # data for "parser" component
    ├── tagger           # data for "tagger" component
    ├── vocab            # model vocabulary
    ├── meta.json        # model meta.json with name, language and pipeline
    └── tokenizer        # tokenization rules
```

When you load the data back in, spaCy will call the custom component's
`from_disk` method with the given file path, and the component can then load the
contents of `data.json`, convert them to a Python object and restore the
component state. The same works for other types of data, of course – for
instance, you could add a
[wrapper for a model](/usage/processing-pipelines#wrapping-models-libraries)
trained with a different library like TensorFlow or PyTorch and make spaCy load
its weights automatically when you load the model package.

<Infobox title="Important note on loading components" variant="warning">

When you load a model from disk, spaCy will check the `"pipeline"` in the
model's `meta.json` and look up the component name in the internal factories. To
make sure spaCy knows how to initialize `"my_component"`, you'll need to add it
to the factories:

```python
from spacy.language import Language
Language.factories["my_component"] = lambda nlp, **cfg: CustomComponent()
```

For more details, see the documentation on
[adding factories](/usage/processing-pipelines#custom-components-factories) or
use [entry points](#entry-points) to make your extension package expose your
custom components to spaCy automatically.

</Infobox>

## Using entry points {#entry-points new="2.1"}

Entry points let you expose parts of a Python package you write to other Python
packages. This lets one application easily customize the behavior of another, by
exposing an entry point in its `setup.py`. For a quick and fun intro to entry
points in Python, check out
[this excellent blog post](https://amir.rachum.com/blog/2017/07/28/python-entry-points/).
spaCy can load custom function from several different entry points to add
pipeline component factories, language classes and other settings. To make spaCy
use your entry points, your package needs to expose them and it needs to be
installed in the same environment – that's it.

| Entry point                                                                    | Description                                                                                                                                                                                                                                              |
| ------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| [`spacy_factories`](#entry-points-components)                                  | Group of entry points for pipeline component factories to add to [`Language.factories`](/usage/processing-pipelines#custom-components-factories), keyed by component name.                                                                               |
| [`spacy_languages`](#entry-points-languages)                                   | Group of entry points for custom [`Language` subclasses](/usage/adding-languages), keyed by language shortcut.                                                                                                                                           |
| `spacy_lookups` <Tag variant="new">2.2</Tag>                                   | Group of entry points for custom [`Lookups`](/api/lookups), including lemmatizer data. Used by spaCy's [`spacy-lookups-data`](https://github.com/explosion/spacy-lookups-data) package.                                                                  |
| [`spacy_displacy_colors`](#entry-points-displacy) <Tag variant="new">2.2</Tag> | Group of entry points of custom label colors for the [displaCy visualizer](/usage/visualizers#ent). The key name doesn't matter, but it should point to a dict of labels and color values. Useful for custom models that predict different entity types. |

### Custom components via entry points {#entry-points-components}

When you load a model, spaCy will generally use the model's `meta.json` to set
up the language class and construct the pipeline. The pipeline is specified as a
list of strings, e.g. `"pipeline": ["tagger", "paser", "ner"]`. For each of
those strings, spaCy will call `nlp.create_pipe` and look up the name in the
[built-in factories](/usage/processing-pipelines#custom-components-factories).
If your model wanted to specify its own custom components, you usually have to
write to `Language.factories` _before_ loading the model.

```python
pipe = nlp.create_pipe("custom_component")  # fails 👎

Language.factories["custom_component"] = CustomComponentFactory
pipe = nlp.create_pipe("custom_component")  # works 👍
```

This is inconvenient and usually required shipping a bunch of component
initialization code with the model. Using entry points, model packages and
extension packages can now define their own `"spacy_factories"`, which will be
added to the built-in factories when the `Language` class is initialized. If a
package in the same environment exposes spaCy entry points, all of this happens
automatically and no further user action is required.

To stick with the theme of
[this entry points blog post](https://amir.rachum.com/blog/2017/07/28/python-entry-points/),
consider the following custom spaCy extension which is initialized with the
shared `nlp` object and will print a snake when it's called as a pipeline
component.

> #### Package directory structure
>
> ```yaml
> ├── snek.py   # the extension code
> └── setup.py  # setup file for pip installation
> ```

```python
### snek.py
snek = """
    --..,_                     _,.--.
       `'.'.                .'`__ o  `;__.
          '.'.            .'.'`  '---'`  `
            '.`'--....--'`.'
              `'--....--'`
"""

class SnekFactory(object):
    def __init__(self, nlp, **cfg):
        self.nlp = nlp

    def __call__(self, doc):
        print(snek)
        return doc
```

Since it's a very complex and sophisticated module, you want to split it off
into its own package so you can version it and upload it to PyPi. You also want
your custom model to be able to define `"pipeline": ["snek"]` in its
`meta.json`. For that, you need to be able to tell spaCy where to find the
factory for `"snek"`. If you don't do this, spaCy will raise an error when you
try to load the model because there's no built-in `"snek"` factory. To add an
entry to the factories, you can now expose it in your `setup.py` via the
`entry_points` dictionary:

```python
### setup.py {highlight="5-7"}
from setuptools import setup

setup(
    name="snek",
    entry_points={
        "spacy_factories": ["snek = snek:SnekFactory"]
    }
)
```

The entry point definition tells spaCy that the name `snek` can be found in the
module `snek` (i.e. `snek.py`) as `SnekFactory`. The same package can expose
multiple entry points. To make them available to spaCy, all you need to do is
install the package:

```bash
$ python setup.py develop
```

spaCy is now able to create the pipeline component `'snek'`:

```
>>> from spacy.lang.en import English
>>> nlp = English()
>>> snek = nlp.create_pipe("snek")  # this now works! 🐍🎉
>>> nlp.add_pipe(snek)
>>> doc = nlp("I am snek")
    --..,_                     _,.--.
       `'.'.                .'`__ o  `;__.
          '.'.            .'.'`  '---'`  `
            '.`'--....--'`.'
              `'--....--'`
```

Arguably, this gets even more exciting when you train your `en_core_snek_sm`
model. To make sure `snek` is installed with the model, you can add it to the
model's `setup.py`. You can then tell spaCy to construct the model pipeline with
the `snek` component by setting `"pipeline": ["snek"]` in the `meta.json`.

> #### meta.json
>
> ```diff
> {
>     "lang": "en",
>     "name": "core_snek_sm",
>     "version": "1.0.0",
> +   "pipeline": ["snek"]
> }
> ```

In theory, the entry point mechanism also lets you overwrite built-in factories
– including the tokenizer. By default, spaCy will output a warning in these
cases, to prevent accidental overwrites and unintended results.

#### Advanced components with settings {#advanced-cfg}

The `**cfg` keyword arguments that the factory receives are passed down all the
way from `spacy.load`. This means that the factory can respond to custom
settings defined when loading the model – for example, the style of the snake to
load:

```python
nlp = spacy.load("en_core_snek_sm", snek_style="cute")
```

```python
SNEKS = {"basic": snek, "cute": cute_snek}  # collection of sneks

class SnekFactory(object):
    def __init__(self, nlp, **cfg):
        self.nlp = nlp
        self.snek_style = cfg.get("snek_style", "basic")
        self.snek = SNEKS[self.snek_style]

    def __call__(self, doc):
        print(self.snek)
        return doc
```

The factory can also implement other pipeline component like `to_disk` and
`from_disk` for serialization, or even `update` to make the component trainable.
If a component exposes a `from_disk` method and is included in a model's
pipeline, spaCy will call it on load. This lets you ship custom data with your
model. When you save out a model using `nlp.to_disk` and the component exposes a
`to_disk` method, it will be called with the disk path.

```python
def to_disk(self, path, **kwargs):
    snek_path = path / "snek.txt"
    with snek_path.open("w", encoding="utf8") as snek_file:
        snek_file.write(self.snek)

def from_disk(self, path, **cfg):
    snek_path = path / "snek.txt"
    with snek_path.open("r", encoding="utf8") as snek_file:
        self.snek = snek_file.read()
    return self
```

The above example will serialize the current snake in a `snek.txt` in the model
data directory. When a model using the `snek` component is loaded, it will open
the `snek.txt` and make it available to the component.

### Custom language classes via entry points {#entry-points-languages}

To stay with the theme of the previous example and
[this blog post on entry points](https://amir.rachum.com/blog/2017/07/28/python-entry-points/),
let's imagine you wanted to implement your own `SnekLanguage` class for your
custom model – but you don't necessarily want to modify spaCy's code to
[add a language](/usage/adding-languages). In your package, you could then
implement the following:

```python
### snek.py
from spacy.language import Language
from spacy.attrs import LANG

class SnekDefaults(Language.Defaults):
    lex_attr_getters = dict(Language.Defaults.lex_attr_getters)
    lex_attr_getters[LANG] = lambda text: "snk"


class SnekLanguage(Language):
    lang = "snk"
    Defaults = SnekDefaults
    # Some custom snek language stuff here
```

Alongside the `spacy_factories`, there's also an entry point option for
`spacy_languages`, which maps language codes to language-specific `Language`
subclasses:

```diff
### setup.py
from setuptools import setup

setup(
    name="snek",
    entry_points={
        "spacy_factories": ["snek = snek:SnekFactory"],
+       "spacy_languages": ["snk = snek:SnekLanguage"]
    }
)
```

In spaCy, you can then load the custom `sk` language and it will be resolved to
`SnekLanguage` via the custom entry point. This is especially relevant for model
packages, which could then specify `"lang": "snk"` in their `meta.json` without
spaCy raising an error because the language is not available in the core
library.

> #### meta.json
>
> ```diff
> {
> -   "lang": "en",
> +   "lang": "snk",
>     "name": "core_snek_sm",
>     "version": "1.0.0",
>     "pipeline": ["snek"]
> }
> ```

```python
from spacy.util import get_lang_class

SnekLanguage = get_lang_class("snk")
nlp = SnekLanguage()
```

### Custom displaCy colors via entry points {#entry-points-displacy new="2.2"}

If you're training a named entity recognition model for a custom domain, you may
end up training different labels that don't have pre-defined colors in the
[`displacy` visualizer](/usage/visualizers#ent). The `spacy_displacy_colors`
entry point lets you define a dictionary of entity labels mapped to their color
values. It's added to the pre-defined colors and can also overwrite existing
values.

> #### Domain-specific NER labels
>
> Good examples of models with domain-specific label schemes are
> [scispaCy](/universe/project/scispacy) and
> [Blackstone](/universe/project/blackstone).

```python
### snek.py
displacy_colors = {"SNEK": "#3dff74", "HUMAN": "#cfc5ff"}
```

Given the above colors, the entry point can be defined as follows. Entry points
need to have a name, so we use the key `colors`. However, the name doesn't
matter and whatever is defined in the entry point group will be used.

```diff
### setup.py
from setuptools import setup

setup(
    name="snek",
    entry_points={
+       "spacy_displacy_colors": ["colors = snek:displacy_colors"]
    }
)
```

After installing the package, the the custom colors will be used when
visualizing text with `displacy`. Whenever the label `SNEK` is assigned, it will
be displayed in `#3dff74`.

import DisplaCyEntSnekHtml from 'images/displacy-ent-snek.html'

<Iframe title="displaCy visualization of entities" html={DisplaCyEntSnekHtml} height={100} />

## Saving, loading and distributing models {#models}

After training your model, you'll usually want to save its state, and load it
back later. You can do this with the
[`Language.to_disk()`](/api/language#to_disk) method:

```python
nlp.to_disk('/home/me/data/en_example_model')
```

The directory will be created if it doesn't exist, and the whole pipeline will
be written out. To make the model more convenient to deploy, we recommend
wrapping it as a Python package.

### Generating a model package {#models-generating}

<Infobox title="Important note" variant="warning">

The model packages are **not suitable** for the public
[pypi.python.org](https://pypi.python.org) directory, which is not designed for
binary data and files over 50 MB. However, if your company is running an
**internal installation** of PyPi, publishing your models on there can be a
convenient way to share them with your team.

</Infobox>

spaCy comes with a handy CLI command that will create all required files, and
walk you through generating the meta data. You can also create the meta.json
manually and place it in the model data directory, or supply a path to it using
the `--meta` flag. For more info on this, see the [`package`](/api/cli#package)
docs.

> #### meta.json
>
> ```json
> {
>   "name": "example_model",
>   "lang": "en",
>   "version": "1.0.0",
>   "spacy_version": ">=2.0.0,<3.0.0",
>   "description": "Example model for spaCy",
>   "author": "You",
>   "email": "you@example.com",
>   "license": "CC BY-SA 3.0",
>   "pipeline": ["tagger", "parser", "ner"]
> }
> ```

```bash
$ python -m spacy package /home/me/data/en_example_model /home/me/my_models
```

This command will create a model package directory that should look like this:

```yaml
### Directory structure
└── /
    ├── MANIFEST.in                   # to include meta.json
    ├── meta.json                     # model meta data
    ├── setup.py                      # setup file for pip installation
    └── en_example_model              # model directory
        ├── __init__.py               # init for pip installation
        └── en_example_model-1.0.0    # model data
```

You can also find templates for all files on
[GitHub](https://github.com/explosion/spacy-models/tree/master/template). If
you're creating the package manually, keep in mind that the directories need to
be named according to the naming conventions of `lang_name` and
`lang_name-version`.

### Customizing the model setup {#models-custom}

The meta.json includes the model details, like name, requirements and license,
and lets you customize how the model should be initialized and loaded. You can
define the language data to be loaded and the
[processing pipeline](/usage/processing-pipelines) to execute.

| Setting    | Type    | Description                                                                                                                                                          |
| ---------- | ------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `lang`     | unicode | ID of the language class to initialize.                                                                                                                              |
| `pipeline` | list    | A list of strings mapping to the IDs of pipeline factories to apply in that order. If not set, spaCy's [default pipeline](/usage/processing-pipelines) will be used. |

The `load()` method that comes with our model package templates will take care
of putting all this together and returning a `Language` object with the loaded
pipeline and data. If your model requires custom
[pipeline components](/usage/processing-pipelines) or a custom language class,
you can also **ship the code with your model**. For examples of this, check out
the implementations of spaCy's
[`load_model_from_init_py`](/api/top-level#util.load_model_from_init_py) and
[`load_model_from_path`](/api/top-level#util.load_model_from_path) utility
functions.

### Building the model package {#models-building}

To build the package, run the following command from within the directory. For
more information on building Python packages, see the docs on Python's
[setuptools](https://setuptools.readthedocs.io/en/latest/).

```bash
$ python setup.py sdist
```

This will create a `.tar.gz` archive in a directory `/dist`. The model can be
installed by pointing pip to the path of the archive:

```bash
$ pip install /path/to/en_example_model-1.0.0.tar.gz
```

You can then load the model via its name, `en_example_model`, or import it
directly as a module and then call its `load()` method.

### Loading a custom model package {#loading}

To load a model from a data directory, you can use
[`spacy.load()`](/api/top-level#spacy.load) with the local path. This will look
for a meta.json in the directory and use the `lang` and `pipeline` settings to
initialize a `Language` class with a processing pipeline and load in the model
data.

```python
nlp = spacy.load("/path/to/model")
```

If you want to **load only the binary data**, you'll have to create a `Language`
class and call [`from_disk`](/api/language#from_disk) instead.

```python
nlp = spacy.blank("en").from_disk("/path/to/data")
```

<Infobox title="Important note: Loading data in v2.x" variant="warning">

In spaCy 1.x, the distinction between `spacy.load()` and the `Language` class
constructor was quite unclear. You could call `spacy.load()` when no model was
present, and it would silently return an empty object. Likewise, you could pass
a path to `English`, even if the mode required a different language. spaCy v2.0
solves this with a clear distinction between setting up the instance and loading
the data.

```diff
- nlp = spacy.load("en_core_web_sm", path="/path/to/data")
+ nlp = spacy.blank("en_core_web_sm").from_disk("/path/to/data")
```

</Infobox>

### How we're training and packaging models for spaCy {#example-training-spacy}

Publishing a new version of spaCy often means re-training all available models,
which is [quite a lot](/usage/models#languages). To make this run smoothly,
we're using an automated build process and a [`spacy train`](/api/cli#train)
template that looks like this:

```bash
$ python -m spacy train {lang} {models_dir}/{name} {train_data} {dev_data} -m meta/{name}.json -V {version} -g {gpu_id} -n {n_epoch} -ns {n_sents}
```

> #### meta.json template
>
> ```json
> {
>   "lang": "en",
>   "name": "core_web_sm",
>   "license": "CC BY-SA 3.0",
>   "author": "Explosion AI",
>   "url": "https://explosion.ai",
>   "email": "contact@explosion.ai",
>   "sources": ["OntoNotes 5", "Common Crawl"],
>   "description": "English multi-task CNN trained on OntoNotes, with GloVe vectors trained on common crawl. Assigns word vectors, context-specific token vectors, POS tags, dependency parse and named entities."
> }
> ```

In a directory `meta`, we keep `meta.json` templates for the individual models,
containing all relevant information that doesn't change across versions, like
the name, description, author info and training data sources. When we train the
model, we pass in the file to the meta template as the `--meta` argument, and
specify the current model version as the `--version` argument.

On each epoch, the model is saved out with a `meta.json` using our template and
added properties, like the `pipeline`, `accuracy` scores and the `spacy_version`
used to train the model. After training completion, the best model is selected
automatically and packaged using the [`package`](/api/cli#package) command.
Since a full meta file is already present on the trained model, no further setup
is required to build a valid model package.

```bash
python -m spacy package -f {best_model} dist/
cd dist/{model_name}
python setup.py sdist
```

This process allows us to quickly trigger the model training and build process
for all available models and languages, and generate the correct meta data
automatically.