# ProgressBarCallback

> **Class** in `langchain_classic`

📖 [View in docs](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback)

A simple progress bar for the console.

## Signature

```python
ProgressBarCallback(
    self,
    total: int,
    ncols: int = 50,
    end_with: str = '\n',
)
```

## Parameters

| Name | Type | Required | Description |
|------|------|----------|-------------|
| `total` | `int` | Yes | The total number of items to be processed. |
| `ncols` | `int` | No | The character width of the progress bar. (default: `50`) |
| `end_with` | `str` | No | Last string to print after progress bar reaches end. (default: `'\n'`) |

## Extends

- `base_callbacks.BaseCallbackHandler`

## Constructors

```python
__init__(
    self,
    total: int,
    ncols: int = 50,
    end_with: str = '\n',
)
```

| Name | Type |
|------|------|
| `total` | `int` |
| `ncols` | `int` |
| `end_with` | `str` |


## Properties

- `total`
- `ncols`
- `end_with`
- `counter`
- `lock`

## Methods

- [`increment()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/increment)
- [`on_chain_error()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_chain_error)
- [`on_chain_end()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_chain_end)
- [`on_retriever_error()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_retriever_error)
- [`on_retriever_end()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_retriever_end)
- [`on_llm_error()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_llm_error)
- [`on_llm_end()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_llm_end)
- [`on_tool_error()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_tool_error)
- [`on_tool_end()`](https://reference.langchain.com/python/langchain-classic/smith/evaluation/progress/ProgressBarCallback/on_tool_end)

---

[View source on GitHub](https://github.com/langchain-ai/langchain/blob/f0c5a28fa05adcda89aebcb449d897245ab21fa4/libs/langchain/langchain_classic/smith/evaluation/progress.py#L14)