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Getting Started with IPython Notebook

The IPython Notebook is a web-based graphical interface to Notebook documents. This Quick Start describes how to:

  • start the IPython Notebook
  • load sample data from a netCDF file
  • draw the data into a map, using various projections

Starting IPython

Let’s look at two ways to use IPython Notebook: local (the default); and remote using a web browser on another computer. The second option is useful when running OSGeo Live in a Virtual Machine (VM).

Local IPython Notebook

Use the application launch menu in the lower left corner.

  • Choose Geospatial -> Spatial Tools -> Start IPython Notebook

A terminal window will open and a startup log will begin to scroll. Next

  • Choose Geospatial -> Spatial Tools -> IPython Notebook

A web browser is automatically launched pointing to the localhost URL at the IPython port number (you should see the Notebook main page). When IPython is launched, the current directory is read for Notebooks. Any sub-directory is shown in the listing (“tree”). The user can navigate up and down the tree by clicking on a directory, or open a Notebook listed by clicking on it. On the computer, Notebook files are just a single text file ending in suffix .ipynb, and are displayed by their filename. Renaming a Notebook simply changes the filename. Creating a new directory will automatically become visible in the IPython Notebook tree browser.

Remote IPython Notebook

  • open a terminal window by clicking on the green terminal icon
  • execute ipython notebook —ip=* —matplotlib=inline —no-browser –port=8883
  • determine the IP address of your computer or VM, for example using: ifconfig -a | grep 192

Use a web browser from another computer and enter the IP address from above, along with the IPython Notebook port ‘:8888’. e.g.

Note: the default http port number for IPython Notebook is 8888. On the OSGeo-Live the Notebook port is set to 8883 to prevent address conflicts with other web applications that use this common number.

Using the IPython Notebook

With the IPython Notebook main page open, you should see the directory tree browser interface, including a directory called OSGeo-live, and a Notebook called cartopy-simple.ipynb. Click on the link titled cartopy_simple.ipynb. A new tab should open in the web browser, showing the Notebook interface. Try moving the mouse over each button in the toolbar and hold it there, to see the tooltip titles. Also take a moment to click on the menus to begin to become familiar with their contents.

Take particular note of the Help menu. You can try the clever User Interface Tour and open the Keyboard Shortcuts cheatsheet, however you will need an active Internet connection to use the other Help topics.

The Notebook interface is a list of cells. Each cell has a type, for example a heading or python code, and consists of one or more lines of text, code, inline image tags or other script. Any cell of type code can be executed by making it active and then clicking on the run button, or using the Run keyboard shortcut Shift-Return.

Try clicking on the first code cell, which includes Import numpy as np and executing it. You should see no error messages, and the next cell downwards becomes active.

To start this Quickstart, it is useful to clear all the stored output in the Notebook. Choose Cell -> All Output -> Clear . All output in the Notebook is now removed.

Importing Data with Python netCDF4

The first Notebook code cell imports important libraries to the active Python interpreter. The second cell assigns a string pathname into variable my_example_nc_file, and then initializes a netCDF4 Dataset object fh. Finally, the third cell reads three Dataset object variables into local numpy ndarrays. For more information about numpy, see .

When you click in the cell with the heading Import Cartopy, Display Example Maps notice the cell type in the toolbar area changes to Markdown.

Display Data using Cartopy

Click or navigate to the next code cell, which begins with %matplotlib inline. This is an IPython Notebook Cell “Magic” - special commands interpreted by the Notebook to change the environment or behavior of the Notebook. This directive tells the Notebook to place matplotlib graphics directly in the window contents, instead of creating a new window. Execute the cell to import matplotlib and cartopy.

In the rest of the Notebook, each cell will draw the sample netCDF data in a different mapping projection. Try executing each cell, and see the results projected in different ways.

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