# Trend Ruby

Ruby client for [Trend](https://github.com/ankane/trend-api), the anomaly detection and forecasting API

**Note: The [hosted version](https://trendapi.org/) is shutting down on May 1, 2024. [See how to run the API on your own infrastructure.](https://github.com/ankane/trend-api)**

[![Build Status](https://github.com/ankane/trend-ruby/workflows/build/badge.svg?branch=master)](https://github.com/ankane/trend-ruby/actions)

## Installation

Add this line to your application’s Gemfile:

```ruby
gem "trend"
```

And set the URL to the API:

```ruby
Trend.url = "http://localhost:8000"
```

## Anomaly Detection

Detect anomalies in a time series

```ruby
# generate series
series = {}
date = Date.parse("2023-04-01")
28.times do
  series[date] = rand(100)
  date += 1
end

# add an anomaly on Apr 21
series[date - 8] = 999

Trend.anomalies(series)
```

Works great with [Groupdate](https://github.com/ankane/groupdate)

```ruby
series = User.group_by_day(:created_at).count
Trend.anomalies(series)
```

## Forecasting

Get future predictions for a time series

```ruby
series = {}
date = Date.parse("2023-04-01")
28.times do
  series[date] = date.wday
  date += 1
end

Trend.forecast(series)
```

Also works great with Groupdate

```ruby
series = User.group_by_day(:created_at).count
Trend.forecast(series)
```

Specify the number of predictions to return

```ruby
Trend.forecast(series, count: 3)
```

## Correlation [experimental]

Get the correlation between two time series

```ruby
Trend.correlation(series, series2)
```

## History

View the [changelog](https://github.com/ankane/trend-ruby/blob/master/CHANGELOG.md)

## Contributing

Everyone is encouraged to help improve this project. Here are a few ways you can help:

- [Report bugs](https://github.com/ankane/trend-ruby/issues)
- Fix bugs and [submit pull requests](https://github.com/ankane/trend-ruby/pulls)
- Write, clarify, or fix documentation
- Suggest or add new features

To get started with development:

```sh
git clone https://github.com/ankane/trend-ruby.git
cd trend-ruby
bundle install
bundle exec rake test
```