# otp.Source.schema

#### *property* Source.schema *: [Schema](#onetick.py.core._source.schema.Schema)*

Represents actual python data schema in the column-name -> type format.
For example, could be used after the [`Source.sink()`](sink.md#onetick.py.Source.sink) to adjust
the schema.

* **Return type:**
  [Schema](#onetick.py.core._source.schema.Schema)

### Examples

```pycon
>>> data = otp.Ticks([['X', 'Y',   'Z'],
...                   [  1, 0.5, 'abc']])
>>> data['T'] = data['Time']
>>> data.schema
{'X': <class 'int'>, 'Y': <class 'float'>, 'Z': <class 'str'>, 'T': <class 'onetick.py.types.nsectime'>}
```

```pycon
>>> data.schema['X']
<class 'int'>
```

```pycon
>>> data.schema['X'] = float
>>> data.schema['X']
<class 'float'>
```

```pycon
>>> 'W' in data.schema
False
>>> data.schema['W'] = otp.nsectime
>>> 'W' in data.schema
True
>>> data.schema['W']
<class 'onetick.py.types.nsectime'>
```

#### SEE ALSO
[`Source.sink`](sink.md#onetick.py.Source.sink)

### *class* Schema

Bases: [`Mapping`](https://docs.python.org/3/library/collections.abc.html#collections.abc.Mapping)

A source data schema proxy. It allows to work with source schema in
a frozen-dict manner. It also allows to set using the `set`
and update a source schema using the `update` methods.

#### items() → a set-like object providing a view on D's items

#### keys() → a set-like object providing a view on D's keys

#### copy()

#### set(\*\*new_schema)

Drops the python schema representation of a source and sets the new one from the new_schema

* **Parameters:**
  **new_schema** (*Dict* *[*[*str*](https://docs.python.org/3/library/stdtypes.html#str) *,* [*type*](https://docs.python.org/3/library/functions.html#type) *]*) -- schema in the column-name -> type format
* **Return type:**
  None

#### update(\*\*other_schema)

Updates the python schema representation of a source: values from matching keys
will be overridden from the other_schema, values from new keys will be added.

* **Parameters:**
  **other_schema** ([*type*](https://docs.python.org/3/library/functions.html#type)) -- schema in the column-name -> type format
* **Return type:**
  None