# Condition-anchored VWAP bands (`ta.anchored_vwap_bands`)



<a id="ta-anchored-vwap-bands"></a>

The center matches condition-anchored VWAP; outer bands use the volume-weighted population standard deviation. Accumulation or output overflow raises an error.

[Indicator catalog](https://docs.openbacktesting.com/reference/indicators/index.md) · [How to use indicators](https://docs.openbacktesting.com/reference/indicator-api/index.md)

## Run this example

This complete script uses bundled data. It observes the selected output without placing trades.

```python
import numpy as np
from openbacktesting import Backtest, Strategy
from openbacktesting.test import GOOG

data = GOOG.copy()
data["source"] = data.Close
data["anchor"] = (np.arange(len(data)) % 20 == 0).astype(float)

class Example(Strategy):
    def init(self):
        self.value = self.ta.anchored_vwap_bands(inputs={'source': 'source', 'volume': 'Volume', 'anchor': 'anchor'})
        self.latest_value = None

    def next(self):
        channel = self.value.vwap
        if channel.valid[-1]:
            self.latest_value = float(channel[-1])

result = Backtest(data, Example).run()
print(result["_strategy"].latest_value)
```

Example inputs: source uses close prices; anchor marks every twentieth bar; replace it with actual period starts.

## Call and parameters

```python
self.ta.anchored_vwap_bands(*, stdev_mult=1.0, inputs=None, backend=None, required_outputs=None)
```

Register in `init()`. Read the returned channel in `next()` after checking `valid[-1]`.

| Parameter | Meaning | Type | Default | Allowed values |
| --- | --- | --- | --- | --- |
| `stdev_mult` | Volume-weighted population standard-deviation multiplier for VWAP bands. | `float` | `1.0` | Minimum: `0.0` |

`source`/named source arguments accept a column name or same-run single-channel handle. Alternatively, `inputs` maps each input below to a column or handle. `backend` selects a supported implementation; `required_outputs` selects channels for readiness diagnostics. See [shared arguments and handles](https://docs.openbacktesting.com/reference/indicator-api/index.md#bind-inputs-and-read-outputs).

## Inputs and outputs

Required inputs: `source`, `volume`, `anchor`.

| Channel | Meaning |
| --- | --- |
| `vwap` | Vwap output |
| `lower` | Lower band |
| `upper` | Upper band |

## Reading values safely

Insufficient history or missing inputs can make a channel invalid. Check that channel's `valid` mask; `ready` is diagnostic and never suppresses `next()`. Multi-output results may have different valid channels on the same bar.

Supply a complete 0/1 anchor series. The example resets every 20 bars only to demonstrate binding; replace it with your intended periods. Exchange sessions are not inferred.

[Indicator catalog](https://docs.openbacktesting.com/reference/indicators/index.md) · [Custom calculations](https://docs.openbacktesting.com/reference/strategy/index.md#register-custom-calculations)