---
output: github_document
bibliography: vignettes/bibliography.bib
---

<!-- README.md is generated from README.Rmd. Please edit that file -->

```{r, include = FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.path = "man/figures/README-",
  out.width = NULL
)
```

# aion <img width=120px src="man/figures/logo.png" align="right" />

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## Overview

Base R ships with a lot of functionality useful for time series, in particular in the **stats** package. However, these features are not adapted to most archaeological time series. These are indeed defined for a given calendar era, they can involve dates very far in the past and the sampling of the observation time is (in most cases) not constant. 

**aion** provides a system of classes and methods to represent and work with such time-series. Dates are represented as *rata die* [@reingold2018], i.e. the number of days since 01-01-01 (Gregorian), with negative values for earlier dates. This allows to represent dates independently of any calendar: it makes calculations and comparisons easier.

Once a time series is created with **aion**, any calendar can be used for printing or plotting data (defaults to Gregorian Common Era; see `vignette("aion")`).

**aion** does not provide tools for temporal modeling. Instead, it offers a simple API that can be used by other specialized packages.

```{r citation, echo=FALSE, comment=''}
utils::citation("aion")
```

## Installation

You can install the released version of **aion** from [CRAN](https://CRAN.R-project.org) with:

```{r cran-installation, eval=FALSE}
install.packages("aion")
```

And the development version from [GitHub](https://github.com/) with:

```{r gh-installation, eval=FALSE}
# install.packages("remotes")
remotes::install_github("tesselle/aion")
```

## Usage

```{r packages-load}
## Load package
library(aion)
```

```{r time-series, fig.width=7, fig.height=5}
## Set seed for reproductibility
set.seed(12345)

## Create 6 time-series of 50 observations
## Sampled every two years starting from 2000 BP
X <- series(
  object = matrix(rnorm(300), nrow = 50, ncol = 6),
  time = seq(from = 2000, by = -2, length.out = 50),
  calendar = calendar("BP")
)

## Plot
plot(X) # Default calendar
```

## Related Works

* [**era**](https://github.com/joeroe/era): provides a consistent representation of year-based time scales as a numeric vector with an associated era.

## Contributing

Please note that the **aion** project is released with a [Contributor Code of Conduct](https://www.tesselle.org/conduct.html). By contributing to this project, you agree to abide by its terms.

## References