<h1><img src="explorer.png" alt="Explorer"></h1>
[](https://hexdocs.pm/explorer)
[](https://hex.pm/packages/explorer)
<!-- MDOC -->
Explorer brings series (one-dimensional) and dataframes (two-dimensional) for fast
data exploration to Elixir.
## Features and design
Explorer high-level features are:
- Simply typed series: `:binary`, `:boolean`, `:category`, `:date`, `:datetime`, `:duration`, `:float`, `:integer`, `:string`, and `:time`.
- A powerful but constrained and opinionated API, so you spend less time looking
for the right function and more time doing data manipulation.
- Support for CSV, Parquet, NDJSON, and Arrow IPC formats
- Integration with external databases via [ADBC](https://github.com/elixir-explorer/adbc)
and direct connection to file storages such as S3
- Pluggable backends, providing a uniform API whether you're working in-memory
or (forthcoming) on remote databases or even Spark dataframes.
- The first (and default) backend is based on NIF bindings to the blazing-fast
[polars](https://docs.rs/polars) library.
The API is heavily influenced by [Tidy Data](https://vita.had.co.nz/papers/tidy-data.pdf)
and borrows much of its design from [dplyr](https://dplyr.tidyverse.org). The philosophy
is heavily influenced by this passage from `dplyr`'s documentation:
> - By constraining your options, it helps you think about your data manipulation
> challenges.
>
> - It provides simple “verbs”, functions that correspond to the most common data
> manipulation tasks, to help you translate your thoughts into code.
>
> - It uses efficient backends, so you spend less time waiting for the computer.
The aim here isn't to have the fastest dataframe library around (though it certainly
helps that [we're building on Polars, one of the fastest](https://h2oai.github.io/db-benchmark/)).
Instead, we're aiming to bridge the best of many worlds:
- the elegance of `dplyr`
- the speed of `polars`
- the joy of Elixir
That means you can expect the guiding principles to be 'Elixir-ish'. For example,
you won't see the underlying data mutated, even if that's the most efficient implementation.
Explorer functions will always return a new dataframe or series.
## Getting started
Inside an Elixir script or [Livebook](https://livebook.dev):
```elixir
Mix.install([
{:explorer, "~> 0.7.0"}
])
```
Or in the `mix.exs` file of your application:
```elixir
def deps do
[
{:explorer, "~> 0.7.0"}
]
end
```
## A glimpse of the API
We have two ways to represent data with Explorer:
- using a series, that is similar to a list, but is guaranteed to contain items
of one data type only - or one *dtype* for short. Notice that nil values are
permitted in series of any dtype.
- using a dataframe, that is just a way to represent one or more series together,
and work with them as a whole. The only restriction is that all the series shares
the same size.
A series can be created from a list:
```elixir
fruits = Explorer.Series.from_list(["apple", "mango", "banana", "orange"])
```
Your newly created series is going to look like:
```
#Explorer.Series<
Polars[4]
string ["apple", "mango", "banana", "orange"]
>
```
And you can, for example, sort that series:
```elixir
Explorer.Series.sort(fruits)
```
Resulting in the following:
```
#Explorer.Series<
Polars[4]
string ["apple", "banana", "mango", "orange"]
>
```
### Dataframes
Dataframes can be created in two ways:
- by reading from files or memory using the
[IO functions](https://hexdocs.pm/explorer/Explorer.DataFrame.html#module-io-operations).
This is by far the most common way to load dataframes in Explorer.
We accept Parquet, IPC, CSV, and NDJSON files.
- by using the `Explorer.DataFrame.new/2` function, that is neat for small experiments.
We are going to use this function here.
You can pass either series or lists to it:
```elixir
mountains = Explorer.DataFrame.new(name: ["Everest", "K2", "Aconcagua"], elevation: [8848, 8611, 6962])
```
Your dataframe is going to look like this:
```
#Explorer.DataFrame<
Polars[3 x 2]
name string ["Everest", "K2", "Aconcagua"]
elevation integer [8848, 8611, 6962]
>
```
It's also possible to see a dataframe like a table, using the `Explorer.DataFrame.print/2`
function:
```elixir
Explorer.DataFrame.print(mountains)
```
Prints:
```
+-------------------------------------------+
| Explorer DataFrame: [rows: 3, columns: 2] |
+---------------------+---------------------+
| name | elevation |
| <string> | <integer> |
+=====================+=====================+
| Everest | 8848 |
+---------------------+---------------------+
| K2 | 8611 |
+---------------------+---------------------+
| Aconcagua | 6962 |
+---------------------+---------------------+
```
And now I want to show you how to filter our dataframe. But first, let's require
the `Explorer.DataFrame` module and give a short name to it:
```elixir
require Explorer.DataFrame, as: DF
```
The "require" is needed to load the macro features of that module.
We give it a shorter name to simplify our examples.
Now let's go to the filter. I want to filter the mountains that are above
the mean elevation in our dataframe:
```elixir
DF.filter(mountains, elevation > mean(elevation))
```
You can see that we can refer to the columns using their names, and use functions
without define them. This is possible due the powerful `Explorer.Query` features,
and it's the main reason we need to "require" the `Explorer.DataFrame` module.
The result is going to look like this:
```
#Explorer.DataFrame<
Polars[2 x 2]
name string ["Everest", "K2"]
elevation integer [8848, 8611]
>
```
There is an extensive guide that you can play with Livebook:
[Ten Minutes to Explorer](https://hexdocs.pm/explorer/exploring_explorer.html)
You can also check the `Explorer.DataFrame` and `Explorer.Series` docs for further
details.
<!-- MDOC -->
## Contributing
Explorer uses Rust for its default backend implementation, and while Rust is not
necessary to use Explorer as a package, you need Rust tooling installed on your
machine if you want to compile from source, which is the case when contributing
to Explorer.
We require Rust Nightly, which can be installed with [Rustup](https://rust-lang.github.io/rustup/installation/index.html).
If you already have Rustup and a recent version of Cargo installed, then the correct version of
Rust is going to be installed in the first compilation of the project. Otherwise, you can manually
install the correct version:
```sh
rustup toolchain install nightly-2023-07-27
```
You can also use [asdf](https://asdf-vm.com/):
```sh
asdf install rust nightly-2023-07-27
```
It's possible that you may need to install [`CMake`](https://cmake.org/) in order to build the project,
if that is not already installed.
Once you have made your changes, run `mix ci`, to lint and format both Elixir
and Rust code.
Our integration tests require the [AWS CLI to be installed](https://docs.aws.amazon.com/cli/latest/userguide/getting-started-install.html),
and also a container engine that can be [Podman](https://podman.io) or [Docker](https://docker.com).
Once these dependencies are installed, you need to run the `mix localstack.setup` command,
and then run the cloud integration tests with `mix test --only cloud_integration`.
Just to recap, here is the combo of commands you need to run:
```sh
mix ci
mix localstack.setup
mix test --only cloud_integration
```
## Precompilation
Explorer ships with the NIF code precompiled for the most popular architectures out there.
We support the following:
- `aarch64-apple-darwin` - MacOS running on ARM 64 bits CPUs.
- `aarch64-unknown-linux-gnu` - Linux running on ARM 64 bits CPUs, compiled with GCC.
- `aarch64-unknown-linux-musl` - Linux running on ARM 64 bits CPUs, compiled with Musl.
- `riscv64gc-unknown-linux-gnu` - Linux running on RISCV 64 bits CPUs, compiled with GCC.
- `x86_64-apple-darwin` - MacOS running on Intel/AMD 64 bits CPUs.
- `x86_64-pc-windows-msvc` - Windows running on Intel/AMD 64 bits CPUs, compiled with Visual C++.
- `x86_64-pc-windows-gnu` - Windows running on Intel/AMD 64 bits CPUs, compiled with GCC.
- `x86_64-unknown-linux-gnu` - Linux running on Intel/AMD 64 bits CPUs, compiled with GCC.
- `x86_64-unknown-linux-musl` - Linux running on Intel/AMD 64 bits CPUs, compiled with Musl.
- `x86_64-unknown-freebsd` - FreeBSD running on Intel/AMD 64 bits.
This means that the problem is going to work without the need to compile it from source.
This currently **only works for Hex releases**. For more information on how it works, please
check the [RustlerPrecompiled project](https://hexdocs.pm/rustler_precompiled).
### Features disabled
Some of the features cannot be compiled to some targets, because one of the dependencies
don't work on it.
This is the case for the **NDJSON** reads and writes, that don't work for the RISCV target.
We also disable the AWS S3 reads and writes for the RISCV target, because one of the dependencies
of `ObjectStore` does not compile on it.
## Sponsors
<a href="https://amplified.ai"><img src="sponsors/amplified.png" width=100 alt="Amplified"></a>
