lets-plot-kotlin

Grammar of Graphics for Kotlin

Programming language: Kotlin

License: MIT License

Tags: Science    

Latest version: v4.1.0

README

Lets-Plot for Kotlin

Latest Lets-Plot Kotlin API Version Latest Lets-Plot Version License

• Overview

• Lets-Plot in Jupyter with Kotlin Kernel

  • Installation
  • "Line Magics"
  • Quick start with Jupyter
  • Example notebooks

• Lets-Plot-Kotlin in Datalore notebooks

• Lets-Plot in JVM and Kotlin/JS application

• Further Reading

  • User guide and API reference
  • Tooltip customization
  • Formatting
  • Data sampling
  • Saving plot to file
  • GeoTools support

• What is new in 4.1.0

• What is new in 4.0.0

  • Migrating to 4.0.0

• Change log

• License

Overview

Lets-Plot for Kotlin is a Kotlin API for the Lets-Plot library - an open-source plotting library for statistical data.

Lets-Plot Kotlin API is built on the principles of layered graphics first described in the Leland Wilkinson work The Grammar of Graphics and later implemented in the ggplot2 package for R.

This grammar [...] is made up of a set of independent components that can be composed in many different ways. This makes [it] very powerful because you are not limited to a set of pre-specified graphics, but you can create new graphics that are precisely tailored for your problem.

• Hadley Wickham, "ggplot2: Elegant Graphics for Data Analysis"

Read Lets-Plot Usage Guide for quick introduction to the Grammar of Graphics and Lets-Plot Kotlin API.

Lets-Plot in Jupyter with Kotlin Kernel

Installation

In Jupyter notebook with a Kotlin Kernel, Lets-Plot library is available out-of-the-box. To install Kotlin Kernel and OpenJDK into a Conda environment, run the following command:

```shell script conda install kotlin-jupyter-kernel -c jetbrains

For more information about Jupyter Kotlin kernel, see
the [Kotlin kernel for Jupyter/iPython](https://github.com/Kotlin/kotlin-jupyter) project.

<a id="line-magics"></a>
#### "Line Magics"

You can include all the necessary Lets-Plot boilerplate code to a notebook using the following "line magic":

%use lets-plot

This will apply the lets-plot `library descriptor` bundled with the Kotlin Jupyter Kernel installed in your environment.

The `%useLatestDescriptors` line magic will force Kotlin Kernel to pull and apply the latest
repository version of all `library descriptors`.

You can override lets-plot `library descriptor` settings using the lets-plot line magic parameters, like:

%use lets-plot(api=1.1.0, lib=1.5.4, js=1.5.4, isolatedFrame=false)

Where:

- `api` - version of Lets-Plot Kotlin API.
- `lib` - version of Lets-Plot library (JAR-s).
- `js`  - version of Lets-PLot JavaScript bundle.
- `isolatedFrame` - If `false`: load JS just once per notebook (default in Jupyter).
  If `true`: include Lets-Plot JS in each output (default in [Datalore notebooks](#datalore))

See: [Line Magics](https://github.com/Kotlin/kotlin-jupyter#line-magics) documentation in the Kotlin Jupyter project for
more details.

<a id="start"></a>
#### Quickstart in Jupyter

- In [Jupyter](https://jupyter-notebook.readthedocs.io/en/stable/index.html), create a new notebook and choose the
  Kotlin kernel (see
  the [instructions](https://jupyter-notebook.readthedocs.io/en/stable/notebook.html?highlight=new#creating-a-new-notebook-document)
  for more details on how to select a kernel).

- Add the following code to a Jupyter notebook:

%use lets-plot

val rand = java.util.Random() val data = mapOf ( "rating" to List(200) { rand.nextGaussian() } + List(200) { rand.nextGaussian() * 1.5 + 1.5 }, "cond" to List(200) { "A" } + List(200) { "B" } )

var p = letsPlot(data) p += geomDensity(color="dark_green", alpha=.3) {x="rating"; fill="cond"} p + ggsize(700, 350)

- Execute the added code to evaluate the plotting capabilities of Lets-Plot.

<img src="https://raw.githubusercontent.com/JetBrains/lets-plot-kotlin/master/docs/examples/images/quickstart.png" alt="Couldn't load quickstart.png" width="500" height="270"/>
<br/>
<a href="https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/quickstart.ipynb" 
   target="_parent"> 
   <img src="https://raw.githubusercontent.com/jupyter/design/master/logos/Badges/nbviewer_badge.png" 
        width="109" height="20">
</a>
<br/>


<a id="jupyter-examples"></a>
#### Example of notebooks

Try the following [examples](https://github.com/JetBrains/lets-plot-kotlin/blob/master/docs/examples.md) to study
features of the `Lets-Plot` library.


<a id="datalore"></a>
## Lets-Plot-Kotlin in Datalore notebooks

[Datalore](https://datalore.jetbrains.com/) is an online data science notebook by JetBrains.

In Datalore notebook you can run Kotlin code directly in your browser. Many popular Kotlin libraries are preinstalled
and readily available
(see the list of [supported Kotlin libraries](https://github.com/Kotlin/kotlin-jupyter#supported-libraries)).

See [Quickstart in Datalore](https://view.datalore.io/notebook/Ybcyrh7ifkvTQVxbTMxaTp) example notebook to learn more
about Kotlin support in Datalore.

Watch the [Datalore Getting Started Tutorial](https://youtu.be/MjvFQxqNSe0) video for a quick introduction to Datalore.


<a id="jvm"></a>
## Lets-Plot in JVM and Kotlin/JS application

Apart from Jupyter notebooks, Lets-Plot library and Kotlin API enables embedding plots into a JVM and a Kotlin/JS
application.

See [README_DEV.md](https://github.com/JetBrains/lets-plot-kotlin/blob/master/README_DEV.md) to learn more about
creating plots in JVM or Kotlin/JS environment.

In the [lets-plot-mini-apps](https://github.com/alshan/lets-plot-mini-apps) GitHub repository you will find examples of
using Lets-Plot Kotlin API in JVM and Kotlin/JS projects.


<a id="further_reading"></a>
## Further Reading

<a id="guide"></a>
#### User guide and API reference

- The User Guide in the form of Jupyter
  notebook: [user_guide.ipynb](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/guide/user_guide.ipynb)
  .

- Lets-Plot Kotlin
  API [reference](https://lets-plot.org/kotlin/index.html).

<a id="tooltip-customization"></a>
#### Tooltip customization

You can customize the content, values formatting and appearance of tooltip for any geometry layer in your plot.

Learn more: [Tooltip Customization](https://github.com/JetBrains/lets-plot-kotlin/blob/master/docs/tooltips.md).

<a id="formatting"></a>
#### Formatting

Formatting of numeric and date-time values in tooltips, legends, on the axes and *text geometry* layer.

Learn more: [Formatting](https://github.com/JetBrains/lets-plot-kotlin/blob/master/docs/formats.md).

<a id="sampling"></a>
#### Data sampling

Sampling is a special technique of data transformation, which helps to deal with large datasets and overplotting.

Learn more: [Data Sampling](https://github.com/JetBrains/lets-plot-kotlin/blob/master/docs/sampling.md).

<a id="export"></a>
#### Saving plot to a file

The `ggsave()` function is a convenient way of saving a plot or a GGBunch object to a file.

The supported export formats are: `SVG, HTML, PNG, JPEG and TIFF`.

For example, the code below will save plot as a PNG image to the file `<user dir>//lets-plot-images/density.png`:

%use lets-plot

val rand = java.util.Random(123) val n = 400 val data = mapOf ( "rating" to List(n/2) { rand.nextGaussian() } + List(n/2) { rand.nextGaussian() * 1.5 + 1.5 }, "cond" to List(n/2) { "A" } + List(n/2) { "B" } )

var p = letsPlot(data) + geomDensity { x = "rating"; color = "cond" } + ggsize(500, 250)

ggsave(p, "density.png")

<img src="https://raw.githubusercontent.com/JetBrains/lets-plot-kotlin/master/docs/examples/images/ggsave_demo.png" alt="Couldn't load ggsave_demo.png" width="500" height="250"/>
<br/>

See `ggsave()` [documentation](https://lets-plot.org/kotlin/-lets--plot--kotlin/org.jetbrains.letsPlot.export/ggsave.html)
for more information about the function arguments and default values.

<a id="geotools"></a>
#### GeoTools support

[GeoTools](https://www.geotools.org/) is an open source Java GIS Toolkit.

Lets-Plot supports visualization of a set of `SimpleFeature`-s stored in `SimpleFeatureCollection`, as well as
individual `Geometry` and `ReferencedEnvelope` objects.

Learn more: [GeoTools Support](https://github.com/JetBrains/lets-plot-kotlin/blob/master/docs/geotools.md).


<a id="new"></a>
## What is new in 4.1.0

- ### Plot Theme

    - #### `themeBW()`

      See: [example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/complete_themes.ipynb).

    - #### Theme Flavors

      Theme flavor offers an easy way to change the colors of all elements in a theme to match a specific color scheme.

      In this release, we have added the following flavors:
        - _darcula_
        - _solarized_light_
        - _solarized_dark_
        - _high_contrast_light_
        - _high_contrast_dark_

  <br>
  <img src="https://raw.githubusercontent.com/JetBrains/lets-plot/master/docs/f-22c/images/theme_flavors.png" alt="f-22c/images/theme_flavors.png" width="1000" height="133">

  See: [example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/theme_flavors.ipynb).

    - #### New parameters in `elementText()`
        - `size, family`
          ([example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/font_size_and_family.ipynb))
        - `hjust, vjust` for plot title, subtitle, caption, legend and axis titles
          ([example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/hjust_vjust.ipynb))
        - `margin` for plot title, subtitle, caption, axis titles and tick labels
          ([example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/text_margins.ipynb))

- ### New Plot Types

  `geomLabel()`.

  See: [example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/geom_label.ipynb).

- ### Color Scales

  Viridis color scales: `scaleColorViridis()`, `scaleFillViridis()`.

  Supported colormaps:
    - _magma_
    - _inferno_
    - _plasma_
    - _viridis_
    - _cividis_
    - _turbo_
    - _twilight_

  <br>
  <img src="https://raw.githubusercontent.com/JetBrains/lets-plot/master/docs/f-22c/images/viridis_plasma.png" alt="f-22c/images/viridis_plasma.png" width="439" height="132">

  See: [example notebook](https://nbviewer.jupyter.org/github/JetBrains/lets-plot-kotlin/blob/master/docs/examples/jupyter-notebooks/colors_viridis.ipynb).

- ### Other improvements and fixes
  See [CHANGELOG.md](https://github.com/JetBrains/lets-plot-kotlin/blob/master/CHANGELOG.md#410---2022-09-30)
  for details.


<a id="new4"></a>
## What is new in 4.0.0

- ### Improvements in the [API reference](https://lets-plot.org/kotlin) documentation

    - Clean navigation tree - non-API elements were removed; improved packages structure
    - References on external documentation, demo-notebooks and, sometimes, code examples were added to many API elements
      and
      packages:
        - [org.jetbrains.letsPlot.sampling](https://lets-plot.org/kotlin/-lets--plot--kotlin/org.jetbrains.letsPlot.sampling/index.html)
        - [geomBin2D](https://lets-plot.org/kotlin/-lets--plot--kotlin/org.jetbrains.letsPlot.geom/geom-bin2-d/index.html) (
          see "Examples" section)

- ### (!) Breaking Changes

  Due to refactorings performed in the source code, the v4.0.0 is no longer backward compatible with earlier versions of
  the Lets-Plot Kotlin API.

  Most notably, all packages were renamed to include the "**org**" prefix in their names.

  See [CHANGELOG.md](https://github.com/JetBrains/lets-plot-kotlin/blob/master/CHANGELOG.md#400---2022-07-25) for more information.  

<a id="migrating4"></a>

### Migrating to 4.0.0

For migration instructions see [Migrating to 4.0.0](https://github.com/JetBrains/lets-plot-kotlin/blob/master/CHANGELOG.md#migrating-to-400) section in the CHANGELOG.


<a id="change_log"></a>
## Change Log

See [CHANGELOG.md](https://github.com/JetBrains/lets-plot-kotlin/blob/master/CHANGELOG.md).


<a id="license"></a>
## License

Code and documentation released under
the [MIT license](https://github.com/JetBrains/lets-plot-kotlin/blob/master/LICENSE).
Copyright © 2019-2022, JetBrains s.r.o.