Tablesaw

Overview

Tablesaw is the shortest path to data science in Java. It includes a dataframe, an embedded column-store, and hundreds of methods to transform, summarize, or filter data similar to the Pandas dataframe and R data frame. If you work with data in Java, it will probably save you time and effort.

Tablesaw also supports descriptive statistics, data visualization, and machine learning. And it scales: You can munge a 1/2 billion rows on a laptop and over 2 billion records on a server.

There are other, more elaborate platforms for data science in Java. They're designed to work with vast amounts of data, and require a huge stack and a vast amount of effort.

Tablesaw 0.8.x and later have new Maven coordinates. You can include tablesaw-core, which is the dataframe library itself, with:

<dependency>
    <groupId>tech.tablesaw</groupId>
    <artifactId>tablesaw-core</artifactId>
    <version>0.9.0</version>
</dependency>

If you'd like to use tablesaw's plotting capabilities you can include tablesaw-plot:

<dependency>
    <groupId>tech.tablesaw</groupId>
    <artifactId>tablesaw-plot</artifactId>
    <version>0.9.0</version>
</dependency>

To include Tablesaw 0.7.x or earlier in your project use:

<dependency>
    <groupId>com.github.lwhite1</groupId>
    <artifactId>tablesaw</artifactId>
    <version>0.7.7.3</version>
</dependency>

Documentation and support:

Please see our documentation page: https://jtablesaw.github.io/tablesaw/

Tablesaw features:

Data processing & transformation

Import data from RDBMS and CSV files, local or remote (http, S3, etc.)
Combine files
Add and remove columns
Sort, Group, Filter
Map/Reduce operations
Store tables in a fast, compressed columnar storage format

Statistics and Machine Learning

Descriptive stats: mean, min, max, median, sum, product, standard deviation, variance, percentiles, geometric mean, skewness, kurtosis, etc.
Regression: Least Squares
Classification: Logistic Regression, Linear Discriminant Analysis, Decision Trees, k-Nearest Neighbors, Random Forests
Clustering: k-Means, x-Means, g-Means
Association: Frequent Item Sets, Association Rule Mining
Feature engineering: Principal Components Analysis

Visualization

Scatter plots
Line plots
Vertical and Horizontal Bar charts
Histograms
Box plots
Quantile Plots
Pareto Charts

Here's an example where we use XChart to map the locations of tornadoes:

You can see examples and read more about plotting in Tablesaw here: https://jtablesaw.wordpress.com/2016/07/30/new-plot-types-in-tablesaw/.

Current performance:

You can load a 500,000,000 row, 4 column csv file (35GB on disk) entirely into about 10 GB of memory. If it's in Tablesaw's .saw format, you can load it in 22 seconds. You can query that table in 1-2 ms: fast enough to use as a cache for a Web app.

BTW, those numbers were achieved on a laptop.

Easy to Use is Easy to Say

The goal in this example is to identify the production shifts with the worst performance. These few lines demonstrate data import, column-wise operations (differenceInSeconds()), filters (isInQ2()) grouping and aggegating (median() and .by()), and (top(n)) calculations.

    Table ops = Table.read().csv("data/operations.csv");                             // load data
    DateTimeColumn start = ops.dateColumn("Date").atTime(ops.timeColumn("Start"));
    DateTimeColumn end = ops.dateColumn("Date").atTime(ops.timeColumn("End");
    LongColumn duration = start.differenceInSeconds(end);                            // calc duration
    duration.setName("Duration");
    ops.addColumn(duration);
    
    Table filtered = ops.selectWhere(                                                // filter
          allOf
              (column("date").isInQ2(),
              (column("SKU").startsWith("429")),
              (column("Operation").isEqualTo("Assembly"))));
   
    Table summary = filtered.median("Duration").by("Facility", "Shift");             // group medians
    FloatArrayList tops = summary.floatColumn("Median").top(5);                      // get "slowest"

If you see something that can be improved, please let us know.

dbrambilla/tablesaw