# Scripts¶

Offers dynamic bot controls by running a user defined script alongside a strategy.

Warning

Currently, Scripts can only be used when running Hummingbot from source or with Docker. Using this feature in the Mac or Windows installers will crash the bot.

## Language¶

As with Hummingbot source code, the script is fully compatible with Python 3.7.

## How it works¶

After configured, the script will start automatically once a strategy starts and it stops when the strategy stops. The script is run on a new dedicated process, in case where the script fails or has a bug, your main Hummingbot application can still function.

1. Create a new script file, you can see examples in the Examples section below, and save it into scripts folder
3. Inside Hummingbot run command config script_enabled and/or config script_file_path
4. Editing conf_global.yml file using a text editor.
 1 2 script_enabled: true script_file_path: spreads_adjusted_on_volatility_script.py 
5. Start running a strategy

## ScriptBase¶

This is the base class (hummingbot/script/script_base.py) for your script, it provides data, events and functions as below.

### Data¶

At every tick, the script gets current market price (mid_price), strategy configuration (pmm_parameters) and total balances (all_total_balances). The mid_price is stored in a list (mid_prices) where a new mid_price is added to the end of the list, whereas strategy configuration and total balances are replaced every time.

Note: The current script feature supports only pure market making strategy configuration.

#### pmm_parameters¶

To set a pure market making strategy parameter to a new value, simply assign a new value to it.

Usage Example: self.pmm_parameters.bid_spread = Decimal("0.03") - to update bid spread to 3%

These below are configurable parameters: - buy_levels (a number of buy orders to place, initially set to order_levels when the strategy starts) - sell_levels (a number of sell orders to place, initially set to order_levels when the strategy starts) - order_levels - bid_spread - ask_spread - order_amount - order_level_spread - order_level_amount - order_refresh_time - order_refresh_tolerance_pct - filled_order_delay - hanging_orders_enabled - hanging_orders_cancel_pct

### Events¶

• on_tick

The code here will be executed on every tick which is every second on a default Hummingbot configuration.

The script will be notified every time a buy order of yours is fully filled. Put in your code logic here to handle such situation if needed.

• on_sell_order_completed

The script will be notified every time a sell order of yours is fully filled. Put in your code logic here to handle such situation if needed.

• on_status

This is called upon status command issued on the Hummingbot application. You can provide your custom status message here.

### Functions¶

• notify

Notifies the user, the message will appear on top left panel of HB application. If Telegram integration enabled, the message will also be sent to the telegram user.

Usage Example: self.notify("Hello world")

• log

Logs message to the strategy log file and display it on Running Logs section of HB.

Usage Example: self.log("Hello world")

• avg_mid_price

Calculates average (mean) of the stored mid prices.

Usage Example: avg_value = self.avg_mid_price(60, 30) - to calculate average mid price at a minute interval for the last 30 minutes

• avg_price_volatility

Calculates average (mean) price volatility, volatility is a price change compared to the previous cycle regardless of its direction, e.g. if price changes -3% (or 3%), the volatility is 3%.

Usage Example: avg_value = self.avg_price_volatility(60, 30) - to calculate average price volatility at a minute interval for the last 30 minutes

• median_price_volatility

Calculates median (middle value) price volatility.

Usage Example: median_value = self.median_price_volatility(60, 30) - to calculate median price volatility at a minute interval for the last 30 minutes

• locate_central_price_volatility

Calculates central located price volatility based on a given mean function. The mean function can be one that is supported by statistics library e.g. mean, median, geometric_mean and many more.

Usage Example: median_value = self.locate_central_price_volatility(60, 30, median) - to calculate median price volatility at a minute interval for the last 30 minutes

• round_by_step

Rounds a given number down by a given step size.

Usage Example: rounded_value = self.round_by_step(1.8, 0.25) will give you 1.75

• take_samples

Takes samples out of a given list where the last item is the most recent. Example List a_list = [1, 2, 3, 4, 5, 6, 7]

Usage Example: samples = self.take_samples(a_list, 3, 2) will give you [4, 7]

## Examples¶

All below examples can be found in scripts\ folder.

• hello_world_script.py

The most basic example only a few lines of code.

• ping_pong_script.py

Replicates our current ping pong strategy using script.

• price_band_script.py

Replicates our current price band strategy using script.

• dynamic_price_band_script.py

Demonstrates how to set the band around mid price moving average, the band moves as the average moves.