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Add 2023 video link, update 2024 schedule (#284)
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* add 2023 video link, update 2024 schedule

* tidy outline

* reorg data structure intro, add malaria example

* Apply suggestions from code review

Co-authored-by: Jessica Scheick <[email protected]>

* local malaria figure, update default links

---------

Co-authored-by: Jessica Scheick <[email protected]>
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scottyhq and JessicaS11 committed Jul 8, 2024
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2 changes: 1 addition & 1 deletion .devcontainer/scipy2024/devcontainer.json
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},
"customizations": {
"codespaces": {
"openFiles": ["workshops/scipy2024/README.md"]
"openFiles": ["workshops/scipy2024/index.ipynb"]
},
"vscode": {
"extensions": ["ms-toolsai.jupyter", "ms-python.python"]
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2 changes: 1 addition & 1 deletion README.md
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[![CI](https://github.com/xarray-contrib/xarray-tutorial/workflows/CI/badge.svg?branch=main)](https://github.com/xarray-contrib/xarray-tutorial/actions?query=branch%3Amain)
[![Jupyter Book Badge](https://jupyterbook.org/badge.svg)](https://tutorial.xarray.dev)
[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/xarray-contrib/xarray-tutorial/HEAD?labpath=overview/fundamental-path/index.ipynb)
[![Binder](https://mybinder.org/badge_logo.svg)](https://mybinder.org/v2/gh/xarray-contrib/xarray-tutorial/HEAD?labpath=workshops/scipy2024/index.ipynb)

This is the repository for a Jupyter Book website with tutorial material for [Xarray](https://github.com/pydata/xarray), _an open source project and Python package that makes working with labelled multi-dimensional arrays simple, efficient, and fun!_

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64 changes: 64 additions & 0 deletions fundamentals/01_data_structures.md
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# Data Structures

Multi-dimensional (a.k.a. N-dimensional, ND) arrays (sometimes called “tensors”)
are an essential part of computational science. They are encountered in a wide
range of fields, including physics, astronomy, geoscience, bioinformatics,
engineering, finance, and deep learning. In Python, [NumPy](https://numpy.org/)
provides the fundamental data structure and API for working with raw ND arrays.
However, real-world datasets are usually more than just raw numbers; they have
labels which encode information about how the array values map to locations in
space, time, etc.

The N-dimensional nature of Xarray’s data structures makes it suitable for
dealing with multi-dimensional scientific data, and its use of dimension names
instead of axis labels (`dim='time'` instead of `axis=0`) makes such arrays much
more manageable than the raw NumPy ndarray: with Xarray, you don’t need to keep
track of the order of an array’s dimensions or insert dummy dimensions of size 1
to align arrays (e.g., using np.newaxis).

The immediate payoff of using Xarray is that you’ll write less code. The
long-term payoff is that you’ll understand what you were thinking when you come
back to look at it weeks or months later.

## Example: Weather forecast

Here is an example of how we might structure a dataset for a weather forecast:

<img src="https://docs.xarray.dev/en/stable/_images/dataset-diagram.png" align="center" width="80%">

You'll notice multiple data variables (temperature, precipitation), coordinate
variables (latitude, longitude), and dimensions (x, y, t). We'll cover how these
fit into Xarray's data structures below.

Xarray doesn’t just keep track of labels on arrays – it uses them to provide a
powerful and concise interface. For example:

- Apply operations over dimensions by name: `x.sum('time')`.

- Select values by label (or logical location) instead of integer location:
`x.loc['2014-01-01']` or `x.sel(time='2014-01-01')`.

- Mathematical operations (e.g., `x - y`) vectorize across multiple dimensions
(array broadcasting) based on dimension names, not shape.

- Easily use the split-apply-combine paradigm with groupby:
`x.groupby('time.dayofyear').mean()`.

- Database-like alignment based on coordinate labels that smoothly handles
missing values: `x, y = xr.align(x, y, join='outer')`.

- Keep track of arbitrary metadata in the form of a Python dictionary:
`x.attrs`.

## Example: Mosquito genetics

Although the Xarray library was originally developed with Earth Science datasets in mind, the datastructures work well across many other domains! For example, below is a side-by-side view of a data schematic on the left and Xarray Dataset representation on the right taken from a mosquito genetics analysis:

![malaria_dataset](../images/malaria_dataset.png)

The data can be stored as a 3-dimensional array, where one dimension of the array corresponds to positions (**variants**) within a reference genome, another dimension corresponds to the individual mosquitoes that were sequenced (**samples**), and a third dimension corresponds to the number of genomes within each individual (**ploidy**)."

You can explore this dataset in detail via the [training course in data analysis for genomic surveillance of African malaria vectors](https://anopheles-genomic-surveillance.github.io/workshop-5/module-1-xarray.html)!

## Explore on your own

The following collection of notebooks provide interactive code examples for working with example datasets and constructing Xarray data structures manually.

```{tableofcontents}
```
141 changes: 34 additions & 107 deletions fundamentals/01_datastructures.ipynb
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"source": [
"# Xarray's Data structures\n",
"\n",
"In this lesson, we cover the basics of Xarray data structures. Our\n",
"learning goals are as follows. By the end of the lesson, we will be able to:\n",
"In this lesson, we cover the basics of Xarray data structures. By the end of the lesson, we will be able to:\n",
"\n",
"- Understand the basic data structures (`DataArray` and `Dataset` objects) in Xarray\n",
"\n",
"---\n",
"\n",
"## Introduction\n",
"\n",
"Multi-dimensional (a.k.a. N-dimensional, ND) arrays (sometimes called “tensors”)\n",
"are an essential part of computational science. They are encountered in a wide\n",
"range of fields, including physics, astronomy, geoscience, bioinformatics,\n",
"engineering, finance, and deep learning. In Python, [NumPy](https://numpy.org/)\n",
"provides the fundamental data structure and API for working with raw ND arrays.\n",
"However, real-world datasets are usually more than just raw numbers; they have\n",
"labels which encode information about how the array values map to locations in\n",
"space, time, etc.\n",
"\n",
"Here is an example of how we might structure a dataset for a weather forecast:\n",
"\n",
"<img src=\"https://docs.xarray.dev/en/stable/_images/dataset-diagram.png\" align=\"center\" width=\"80%\">\n",
"\n",
"You'll notice multiple data variables (temperature, precipitation), coordinate\n",
"variables (latitude, longitude), and dimensions (x, y, t). We'll cover how these\n",
"fit into Xarray's data structures below.\n",
"\n",
"Xarray doesn’t just keep track of labels on arrays – it uses them to provide a\n",
"powerful and concise interface. For example:\n",
"\n",
"- Apply operations over dimensions by name: `x.sum('time')`.\n",
"\n",
"- Select values by label (or logical location) instead of integer location:\n",
" `x.loc['2014-01-01']` or `x.sel(time='2014-01-01')`.\n",
"\n",
"- Mathematical operations (e.g., `x - y`) vectorize across multiple dimensions\n",
" (array broadcasting) based on dimension names, not shape.\n",
"\n",
"- Easily use the split-apply-combine paradigm with groupby:\n",
" `x.groupby('time.dayofyear').mean()`.\n",
"\n",
"- Database-like alignment based on coordinate labels that smoothly handles\n",
" missing values: `x, y = xr.align(x, y, join='outer')`.\n",
"\n",
"- Keep track of arbitrary metadata in the form of a Python dictionary:\n",
" `x.attrs`.\n",
"\n",
"The N-dimensional nature of xarray’s data structures makes it suitable for\n",
"dealing with multi-dimensional scientific data, and its use of dimension names\n",
"instead of axis labels (`dim='time'` instead of `axis=0`) makes such arrays much\n",
"more manageable than the raw numpy ndarray: with xarray, you don’t need to keep\n",
"track of the order of an array’s dimensions or insert dummy dimensions of size 1\n",
"to align arrays (e.g., using np.newaxis).\n",
"\n",
"The immediate payoff of using xarray is that you’ll write less code. The\n",
"long-term payoff is that you’ll understand what you were thinking when you come\n",
"back to look at it weeks or months later.\n"
":::{admonition} Learning Goals\n",
"- Understand the basic Xarray data structures `DataArray` and `Dataset` \n",
"- Customize the display of Xarray data structures\n",
"- The connection between Pandas and Xarray data structures\n",
":::"
]
},
{
Expand All @@ -72,13 +23,10 @@
"\n",
"Xarray provides two data structures: the `DataArray` and `Dataset`. The\n",
"`DataArray` class attaches dimension names, coordinates and attributes to\n",
"multi-dimensional arrays while `Dataset` combines multiple arrays.\n",
"multi-dimensional arrays while `Dataset` combines multiple DataArrays.\n",
"\n",
"Both classes are most commonly created by reading data.\n",
"To learn how to create a DataArray or Dataset manually, see the [Creating Data Structures](01.1_creating_data_structures.ipynb) tutorial.\n",
"\n",
"Xarray has a few small real-world tutorial datasets hosted in this GitHub repository https://github.com/pydata/xarray-data.\n",
"We'll use the [xarray.tutorial.load_dataset](https://docs.xarray.dev/en/stable/generated/xarray.tutorial.open_dataset.html#xarray.tutorial.open_dataset) convenience function to download and open the `air_temperature` (National Centers for Environmental Prediction) Dataset by name."
"To learn how to create a DataArray or Dataset manually, see the [Creating Data Structures](01.1_creating_data_structures.ipynb) tutorial."
]
},
{
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"outputs": [],
"source": [
"import numpy as np\n",
"import xarray as xr"
"import xarray as xr\n",
"import pandas as pd\n",
"\n",
"# When working in a Jupyter Notebook you might want to customize Xarray display settings to your liking\n",
"# The following settings reduce the amount of data displayed out by default\n",
"xr.set_options(display_expand_attrs=False, display_expand_data=False)\n",
"np.set_printoptions(threshold=10, edgeitems=2)"
]
},
{
Expand All @@ -97,7 +51,10 @@
"source": [
"### Dataset\n",
"\n",
"`Dataset` objects are dictionary-like containers of DataArrays, mapping a variable name to each DataArray.\n"
"`Dataset` objects are dictionary-like containers of DataArrays, mapping a variable name to each DataArray.\n",
"\n",
"Xarray has a few small real-world tutorial datasets hosted in this GitHub repository https://github.com/pydata/xarray-data.\n",
"We'll use the [xarray.tutorial.load_dataset](https://docs.xarray.dev/en/stable/generated/xarray.tutorial.open_dataset.html#xarray.tutorial.open_dataset) convenience function to download and open the `air_temperature` (National Centers for Environmental Prediction) Dataset by name."
]
},
{
Expand Down Expand Up @@ -147,14 +104,14 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"#### What is all this anyway? (String representations)\n",
"#### HTML vs text representations\n",
"\n",
"Xarray has two representation types: `\"html\"` (which is only available in\n",
"notebooks) and `\"text\"`. To choose between them, use the `display_style` option.\n",
"\n",
"So far, our notebook has automatically displayed the `\"html\"` representation (which we will continue using).\n",
"The `\"html\"` representation is interactive, allowing you to collapse sections (left arrows) and\n",
"view attributes and values for each value (right hand sheet icon and data symbol)."
"The `\"html\"` representation is interactive, allowing you to collapse sections () and\n",
"view attributes and values for each value (📄 and )."
]
},
{
Expand All @@ -171,18 +128,13 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"The output consists of:\n",
"☝️ From top to bottom the output consists of:\n",
"\n",
"- a summary of all *dimensions* of the `Dataset` `(lat: 25, time: 2920, lon: 53)`: this tells us that the first\n",
" dimension is named `lat` and has a size of `25`, the second dimension is named\n",
" `time` and has a size of `2920`, and the third dimension is named `lon` and has a size\n",
" of `53`. Because we will access the dimensions by name, the order doesn't matter.\n",
"- an unordered list of *coordinates* or dimensions with coordinates with one item\n",
" per line. Each item has a name, one or more dimensions in parentheses, a dtype\n",
" and a preview of the values. Also, if it is a dimension coordinate, it will be\n",
" marked with a `*`.\n",
"- an alphabetically sorted list of *dimensions without coordinates* (if there are any)\n",
"- an unordered list of *attributes*, or metadata"
"- **Dimensions**: summary of all *dimensions* of the `Dataset` `(lat: 25, time: 2920, lon: 53)`: this tells us that the first dimension is named `lat` and has a size of `25`, the second dimension is named `time` and has a size of `2920`, and the third dimension is named `lon` and has a size of `53`. Because we will access the dimensions by name, the order doesn't matter.\n",
"- **Coordinates**: an unordered list of *coordinates* or dimensions with coordinates with one item per line. Each item has a name, one or more dimensions in parentheses, a dtype and a preview of the values. Also, if it is a dimension coordinate, it will be printed in **bold** font. *dimensions without coordinates* appear in plain font (there are none in this example, but you might imagine a 'mask' coordinate that has a value assigned at every point).\n",
"- **Data variables**: names of each nD *measurement* in the dataset, followed by its dimensions `(time, lat, lon)`, dtype, and a preview of values.\n",
"- **Indexes**: Each dimension with coordinates is backed by an \"Index\". In this example, each dimension is backed by a `PandasIndex`\n",
"- **Attributes**: an unordered list of metadata (for example, a paragraph describing the dataset)"
]
},
{
Expand Down Expand Up @@ -379,15 +331,6 @@
"methods on `xarray` objects:\n"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": [
"import pandas as pd"
]
},
{
"cell_type": "code",
"execution_count": null,
Expand Down Expand Up @@ -429,8 +372,8 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"**<code>to_series</code>**: This will always convert `DataArray` objects to\n",
"`pandas.Series`, using a `MultiIndex` for higher dimensions\n"
"### to_series\n",
"This will always convert `DataArray` objects to `pandas.Series`, using a `MultiIndex` for higher dimensions\n"
]
},
{
Expand All @@ -446,9 +389,10 @@
"cell_type": "markdown",
"metadata": {},
"source": [
"**<code>to_dataframe</code>**: This will always convert `DataArray` or `Dataset`\n",
"objects to a `pandas.DataFrame`. Note that `DataArray` objects have to be named\n",
"for this.\n"
"### to_dataframe\n",
"\n",
"This will always convert `DataArray` or `Dataset` objects to a `pandas.DataFrame`. Note that `DataArray` objects have to be named for this. Since columns in a `DataFrame` need to have the same index, they are\n",
"broadcasted."
]
},
{
Expand All @@ -459,23 +403,6 @@
"source": [
"ds.air.to_dataframe()"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Since columns in a `DataFrame` need to have the same index, they are\n",
"broadcasted.\n"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": [
"ds.to_dataframe()"
]
}
],
"metadata": {
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4 changes: 4 additions & 0 deletions workshops/scipy2023/README.md
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## Instructions

:::{note}
You can access a recording of this tutorial [here](https://www.youtube.com/watch?v=L4FXcIOMlsY)
:::

### Running Locally

See instructions to set up the environment for running the tutorial material [here](get-started).
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15 changes: 9 additions & 6 deletions workshops/scipy2024/index.ipynb
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"\n",
"**Xarray**: *Friendly, Interactive, and Scalable Scientific Data Analysis*\n",
"\n",
"July 8, 13:30–17:30 (US/Pacific), Room 317\n",
"July 8, 13:30–17:30 (US/Pacific), Tacoma Convention Center Ballroom B/C\n",
"\n",
"This *4-hour* workshop will explore content from [the Xarray tutorial](https://tutorial.xarray.dev), which contains a comprehensive collection of hands-on tutorial Jupyter Notebooks. We will review a curated set of examples that will prepare you for increasingly complex real-world data analysis tasks!\n",
"\n",
":::{admonition} Learning Goals\n",
"- Orient yourself to Xarray resources to continue on your Xarray journey!\n",
"- Effectively use Xarray’s multidimensional indexing and computational patterns\n",
"- Understand how Xarray can wrap other array types in the scientific Python ecosystem\n",
"- Understand how Xarray integrates with other libraries in the scientific Python ecosystem\n",
"- Learn how to leverage Xarray’s powerful backend and extension capabilities to customize workflows and open a variety of scientific datasets\n",
":::\n",
"\n",
Expand All @@ -33,13 +33,13 @@
"| Topic | Time | Notebook Links | \n",
"| :- | - | - | \n",
"| Introduction and Setup | 1:30 (10 min) | --- | \n",
"| Xarray Data Model, Backends, Extensions | 1:40 (40 min) | [Quick Introduction to Indexing](../../fundamentals/02.1_indexing_Basic.ipynb) <br> [Boolean Indexing & Masking](../../intermediate/indexing/boolean-masking-indexing.ipynb) | \n",
"| The Xarray Data Model | 1:40 (40 min) | [Data structures](../../fundamentals/01_data_structures.md) <br> [Basic Indexing](../../fundamentals/02.1_indexing_Basic.ipynb) | \n",
"| *10 minute Break* \n",
"| Computational Patterns | 2:30 (50 min) | [Advanced Indexing](../../intermediate/indexing/advanced-indexing.ipynb) <br> [Computation Patterns](../../intermediate/01-high-level-computation-patterns.ipynb) <br> | \n",
"| Indexing & Computational Patterns | 2:30 (50 min) | [Advanced Indexing](../../intermediate/indexing/indexing.md) <br> [Computational Patterns](../../intermediate/01-high-level-computation-patterns.ipynb) <br> | \n",
"| *10 minute Break* | \n",
"| Wrapping other arrays | 3:30 (50 min) | [The Xarray Ecosystem](../../intermediate/xarray_ecosystem.ipynb) <br> [Accessors](../../advanced/accessors/01_accessor_examples.ipynb) <br> [Backends](../../advanced/backends/1.Backend_without_Lazy_Loading.ipynb) <br> | \n",
"| Xarray Integrations and Extensions | 3:30 (50 min) | [The Xarray Ecosystem](../../intermediate/xarray_ecosystem.ipynb) | \n",
"| *10 minute Break* | \n",
"| Synthesis, Explore your data! | 4:30 (50 min) <br> | [Data Tidying](../../intermediate/data_cleaning/05.1_intro.md) <br> |\n",
"| Backends & Remote data| 4:30 (50 min) | [Remote Data](../../intermediate/remote_data/remote-data.ipynb) |\n",
"| | End 5:30 | |\n",
"\n",
"\n",
Expand All @@ -66,6 +66,9 @@
"- Once you see a url to click within the terminal, simply `cmd + click` the given url.\n",
"- This will open up another tab in your browser, leading to a [Jupyter Lab](https://jupyterlab.readthedocs.io/en/latest/) Interface.\n",
"\n",
":::{warning}\n",
"Consider Codespaces as ephemeral environments. You may lose your connection and any edits you make.\n",
":::\n",
"\n",
"\n",
"## Thanks for attending!\n",
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