# otp.Source.character_present

#### Source.character_present(field, characters, characters_field='', discard_on_match=False, inplace=False)

Propagates ticks based on whether the value of the field specified by field contains a character
in the set of characters specified by characters.
Uses **CHARACTER_PRESENT** EP.

* **Parameters:**
  * **field** (str, [`Column`](../operation/root.md#onetick.py.Column)) -- Name of the field (must be present in the input tick descriptor).
  * **characters** ([*str*](https://docs.python.org/3/library/stdtypes.html#str) *,* *List* *[*[*str*](https://docs.python.org/3/library/stdtypes.html#str) *]*) -- A set of characters that are searched for in the value of the field.
    If set as string, works as list of characters.
  * **characters_field** (str, [`Column`](../operation/root.md#onetick.py.Column)) -- If specified, will take a current value of that field and append it to characters, if any.
  * **discard_on_match** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) -- When set to `True` only ticks that did not match the filter are propagated,
    otherwise ticks that satisfy the filter condition are propagated.
  * **inplace** ([*bool*](https://docs.python.org/3/library/functions.html#bool)) -- The flag controls whether operation should be applied inplace or not.
    If `inplace=True`, then it returns nothing.
    Otherwise, method returns a new modified object.
  * **self** ([*Source*](root.md#onetick.py.Source))
* **Return type:**
  [`Source`](root.md#onetick.py.Source) or `None`

### Examples

Select ticks that have the N or T in EXCHANGE field

```pycon
>>> data = otp.DataSource('TEST_DATABASE', tick_type='TRD', symbols='A')  
>>> data = data[['PRICE', 'SIZE', 'EXCHANGE']]  
>>> data = data.character_present(field=data['EXCHANGE'], characters='NT')  
>>> otp.run(data)  
                     Time  PRICE   SIZE EXCHANGE
0 2003-12-01 00:00:00.000  28.44  55100        N
1 2003-12-01 00:00:00.001  28.44    100        T
2 2003-12-01 00:00:00.002  28.44    200        T
3 2003-12-01 00:00:00.003  28.45    100        T
4 2003-12-01 00:00:00.004  28.44    500        T
```

Select ticks that have the N or T in EXCHANGE field and character set in OLD_EXCHANGE field

```pycon
>>> data = otp.DataSource('TEST_DATABASE', tick_type='TRD', symbols='A')  
>>> data = data.character_present(  
...     field=data['EXCHANGE'], characters='NT', characters_field=data['OLD_EXCHANGE'],
... )
>>> data = data[['PRICE', 'SIZE', 'EXCHANGE']]  
>>> otp.run(data)  
                     Time  PRICE   SIZE EXCHANGE
0 2003-12-01 00:00:00.000  28.44  55100        N
1 2003-12-01 00:00:00.001  28.44    100        B
2 2003-12-01 00:00:00.002  28.44    200        B
3 2003-12-01 00:00:00.003  28.45    100        T
4 2003-12-01 00:00:00.004  28.44    200        T
```

#### SEE ALSO
**CHARACTER_PRESENT** OneTick event processor