100 lines
3.6 KiB
Markdown
100 lines
3.6 KiB
Markdown
go-chart
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========
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[](https://travis-ci.org/wcharczuk/go-chart) [](https://goreportcard.com/report/github.com/wcharczuk/go-chart)
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Package `chart` is a very simple golang native charting library that supports timeseries and continuous
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line charts.
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The v1.0 release has been tagged so things should be more or less stable, if something changes please log an issue.
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Master should now be on the v2.x codebase, which brings a couple new features and better handling of basics like axes labeling etc. Per usual, see `_examples` for more information.
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# Installation
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To install `chart` run the following:
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```bash
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> go get -u github.com/wcharczuk/go-chart
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```
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Most of the components are interchangeable so feel free to crib whatever you want.
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# Output Examples
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Spark Lines:
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Single axis:
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Two axis:
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# Other Chart Types
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Pie Chart:
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The code for this chart can be found in `_examples/pie_chart/main.go`.
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Stacked Bar:
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The code for this chart can be found in `_examples/stacked_bar/main.go`.
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# Code Examples
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Actual chart configurations and examples can be found in the `./_examples/` directory. They are web servers, so start them with `go run main.go` then access `http://localhost:8080` to see the output.
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# Usage
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Everything starts with the `chart.Chart` object. The bare minimum to draw a chart would be the following:
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```golang
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import (
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...
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"bytes"
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...
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"github.com/wcharczuk/go-chart" //exposes "chart"
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)
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graph := chart.Chart{
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Series: []chart.Series{
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chart.ContinuousSeries{
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XValues: []float64{1.0, 2.0, 3.0, 4.0},
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YValues: []float64{1.0, 2.0, 3.0, 4.0},
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},
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},
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}
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buffer := bytes.NewBuffer([]byte{})
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err := graph.Render(chart.PNG, buffer)
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```
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Explanation of the above: A `chart` can have many `Series`, a `Series` is a collection of things that need to be drawn according to the X range and the Y range(s).
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Here, we have a single series with x range values as float64s, rendered to a PNG. Note; we can pass any type of `io.Writer` into `Render(...)`, meaning that we can render the chart to a file or a resonse or anything else that implements `io.Writer`.
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# API Overview
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Everything on the `chart.Chart` object has defaults that can be overriden. Whenever a developer sets a property on the chart object, it is to be assumed that value will be used instead of the default. One complication here
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is any object's root `chart.Style` object (i.e named `Style`) and the `Show` property specifically, if any other property is set and the `Show` property is unset, it is assumed to be it's default value of `False`.
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The best way to see the api in action is to look at the examples in the `./_examples/` directory.
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# Design Philosophy
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I wanted to make a charting library that used only native golang, that could be stood up on a server (i.e. it had built in fonts).
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The goal with the API itself is to have the "zero value be useful", and to require the user to not code more than they absolutely needed.
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# Contributions
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This library is super early but contributions are welcome.
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