quickchart-io 2.0.0
A client for quickchart.io, a service that generates static chart images
License: MIT
Requires Python: >=3.7,<4
Keywords: chart api,chart image,charts

# quickchart-python
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A Python client for the [quickchart.io](https://quickchart.io/) image charts web service.

# Installation

Use the `quickchart.py` library in this project, or install through [pip](https://pypi.org/project/quickchart.io/):

```
pip install quickchart.io
```

# Usage

This library provides a `QuickChart` class.  Import and instantiate it.  Then set properties on it and specify a [Chart.js](https://chartjs.org) config:

```python
from quickchart import QuickChart

qc = QuickChart()
qc.width = 500
qc.height = 300
qc.config = {
    "type": "bar",
    "data": {
        "labels": ["Hello world", "Test"],
        "datasets": [{
            "label": "Foo",
            "data": [1, 2]
        }]
    }
}
```

Use `get_url()` on your quickchart object to get the encoded URL that renders your chart:

```python
print(qc.get_url())
# https://quickchart.io/chart?c=%7B%22chart%22%3A+%7B%22type%22%3A+%22bar%22%2C+%22data%22%3A+%7B%22labels%22%3A+%5B%22Hello+world%22%2C+%22Test%22%5D%2C+%22datasets%22%3A+%5B%7B%22label%22%3A+%22Foo%22%2C+%22data%22%3A+%5B1%2C+2%5D%7D%5D%7D%7D%7D&w=600&h=300&bkg=%23ffffff&devicePixelRatio=2.0&f=png
```

If you have a long or complicated chart, use `get_short_url()` to get a fixed-length URL using the quickchart.io web service (note that these URLs only persist for a short time unless you have a subscription):

```python
print(qc.get_short_url())
# https://quickchart.io/chart/render/f-a1d3e804-dfea-442c-88b0-9801b9808401
```

The URLs will render an image of a chart:

<img src="https://quickchart.io/chart?c=%7B%22type%22%3A+%22bar%22%2C+%22data%22%3A+%7B%22labels%22%3A+%5B%22Hello+world%22%2C+%22Test%22%5D%2C+%22datasets%22%3A+%5B%7B%22label%22%3A+%22Foo%22%2C+%22data%22%3A+%5B1%2C+2%5D%7D%5D%7D%7D&w=600&h=300&bkg=%23ffffff&devicePixelRatio=2.0&f=png" width="500" />

# Using Javascript functions in your chart

Chart.js sometimes relies on Javascript functions (e.g. for formatting tick labels).  There are a couple approaches:

  - Build chart configuration as a string instead of a Python object.  See `examples/simple_example_with_function.py`.
  - Build chart configuration as a Python object and include a placeholder string for the Javascript function.  Then, find and replace it.
  - Use the provided `QuickChartFunction` class.  See `examples/using_quickchartfunction.py` for a full example.

A short example using `QuickChartFunction`:
```py
qc = QuickChart()
qc.config = {
    "type": "bar",
    "data": {
        "labels": ["A", "B"],
        "datasets": [{
            "label": "Foo",
            "data": [1, 2]
        }]
    },
    "options": {
        "scales": {
            "yAxes": [{
                "ticks": {
                    "callback": QuickChartFunction('(val) => val + "k"')
                }
            }],
            "xAxes": [{
                "ticks": {
                    "callback": QuickChartFunction('''function(val) {
                      return val + '???';
                    }''')
                }
            }]
        }
    }
}

print(qc.get_url())
```

# Customizing your chart

You can set the following properties:

### config: dict or str
The actual Chart.js chart configuration.

### width: int
Width of the chart image in pixels.  Defaults to 500

### height: int
Height of the chart image  in pixels.  Defaults to 300

### format: str
Format of the chart. Defaults to png. svg is also valid.

### background_color: str
The background color of the chart. Any valid HTML color works. Defaults to #ffffff (white). Also takes rgb, rgba, and hsl values.

### device_pixel_ratio: float
The device pixel ratio of the chart. This will multiply the number of pixels by the value. This is usually used for retina displays. Defaults to 1.0.

### version: str
The version of Chart.js to use. Acceptable values are documented [here](https://quickchart.io/documentation/#parameters). Usually used to select Chart.js 3+.

### host
Override the host of the chart render server. Defaults to quickchart.io.

### key
Set an API key that will be included with the request.

## Getting URLs

There are two ways to get a URL for your chart object.

### get_url(): str

Returns a URL that will display the chart image when loaded.

### get_short_url(): str

Uses the quickchart.io web service to create a fixed-length chart URL that displays the chart image.  Returns a URL such as `https://quickchart.io/chart/render/f-a1d3e804-dfea-442c-88b0-9801b9808401`.

Note that short URLs expire after a few days for users of the free service.  You can [subscribe](https://quickchart.io/pricing/) to keep them around longer.

## Other functionality

### get_bytes()

Returns the bytes representing the chart image.

### to_file(path: str)

Writes the chart image to a file path.

## More examples

Checkout the `examples` directory to see other usage.