OMG! Tablesaw, a Java data visualization library!

Related learning recommendations: java basic tutorial

##This article is suitable for people who have just learned the basics of the Java language , follow this article to understand and use Tablesaw projects. The examples are all demonstrated under the Windows operating system

HelloGitHub launched the "Explanation of Open Source Projects" series. Today we bring you an open source project of a data visualization library based on the Java language -

Tablesaw

Tablesaw is a Java data visualization library. It mainly consists of two parts: one is the data parsing library and the other is the data visualization library. The data parsing library mainly loads data and operates on the data (conversion, filtering, summary, etc.). The data visualization library converts target data into visual charts.

Project source code address: github.com/jtablesaw/t…

1. Project structure

Directory description:

aggregate: Maven's project parent project, mainly defines the configuration of project packaging.
1. beakerx: The registry of the tablesaw library, the main registry and columns.
2. core: The core code of the tablesaw library, mainly data processing operations: data appending, sorting, grouping, query, etc.
3. data: Project test data directory.
4. docs: Project MarkDown documentation directory.
5. docs-src: Project document source code directory, its main function is to generate MarkDown documents.
6. excel: A sub-project that parses excel file data.
7. html: A sub-project that parses html file data.
8. json: A sub-project that parses json file data.
9. jsplot: A sub-project of data visualization, its main function is to load data and generate visual charts.
10. saw: tablesaw sub-project for reading and writing chart data.

2. Practical operation

2.1 Preparation work

Introducing the Tablesaw dependency package into the project

<dependency>
    <groupid>tech.tablesaw</groupid>
    <artifactid>tablesaw-core</artifactid>
    <version>LATEST</version></dependency>复制代码

2.2 Data analysis

2.2.1 Internal data production data table

@Testpublic void tableSawTest6() {
	String[] students = {"小明", "李雷", "小二"};	double[] scores = {90.1, 84.3, 99.7};
	Table table = Table.create("学生分数统计表").addColumns(
					StringColumn.create("姓名", students),
					DoubleColumn.create("分数", scores));
	System.out.println(table.print());
}复制代码

The code is super simple. First, define the column data students and scores to be displayed. Then create a table for data display, define the table name, and add table column data.

The effect is shown as follows:

##2.2.2 Load the data file to create the data table

@Testpublic void tableSawTest10() throws Exception{
	Table table = Table.read().csv("/data/bush.csv");
	Table whoPercents = table.xTabPercents("who");
	whoPercents.columnsOfType(ColumnType.DOUBLE)
	.forEach(x -> ((NumberColumn) x).setPrintFormatter(
		NumberColumnFormatter.percent(0)));
	System.out.println(whoPercents.toString());
}复制代码

First

Table.read

Load data files, loading data supports csv, database result sets, files, URLs, etc. Specify the fields of the x-axis of the table, and convert the data into percentage data.

The content of the bash.csv file is as follows:

##The running effect is as follows:

2.3 Data Visualization

Table robberies = Table.read().csv("./data/boston-robberies.csv");
Plot.show(
	AreaPlot.create(		"Boston Robberies by month: Jan 1966-Oct 1975", 
		robberies, "Record", "Robberies"));复制代码

First load the data

Table.read

, draw the chart

AreaPlot.create, and thenPlot. show Generate the html page of the chart locally and automatically open the browser for display. boston-robberies.csv file content is as follows:

The running effect is as follows:

Tablesaw can also draw many types of charts, looking forward to your exploration.

3. Finally

At this point in the tutorial, you should have a simple understanding of Tablesaw. Here is a way to quickly master the open source library:

Find the unit test code of the project in the source code. Then, we import the project into the development tool and directly run the unit tests in the project.

This is probably the fastest and most effective way to master and get started with open source libraries.

This tutorial is for those who have a certain Java programming foundation. If your project happens to require a data visualization library, the Tablesaw library is a good choice!

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