EDS 217 Cheatsheet

JupyterLab Basics: Variable Inspection, Magic Commands, and Shortcuts

Variable Inspection in JupyterLab

Installing the Variable Inspector Extension

Before we can use the Variable Inspector in JupyterLab, we need to install the extension. Follow these steps:

  1. Start a new JupyterLab session in your web browser.

  2. Click on the β€œ+” button in the top left corner to open the Launcher (it might already be opened).

  3. Under β€œOther”, click on β€œTerminal” to open a new terminal session.

  4. In the terminal, type the following command and press Enter:

    pip install lckr-jupyterlab-variableinspector

  5. Wait for the installation to complete. You should see a message indicating successful installation.

  6. Once the installation is complete, you need to restart JupyterLab for the changes to take effect. To do this:

    • Save all your open notebooks and files.
    • Close all browser tabs with JupyterLab.
    • Login to https://workbench-1.bren.ucsb.edu again.
    • Restart a JupyterLab session

After restarting JupyterLab, the Variable Inspector extension should be available for use.

Variable Inspector

Now that you have installed the Variable Inspector extension, here’s how to use it:

Open the Variable Inspector: - Menu: View > Activate Command Palette, then type β€œvariable inspector” - Shortcut: Ctrl + Shift + I (Windows/Linux) or Cmd + Shift + I (Mac) - Right-click in an open notebook and select β€œOpen Variable Inspector” (will be at the bottom of the list)

The Variable Inspector shows: - Variable names - Types - Values/shapes - Count (for collections)

Limits to the Variable Inspector

The variable inspector is not suitable for use with large dataframes or large arrays. You should use standard commands like df.head(), df.tail(), df.info(), df.describe() to inspect large dataframes.

Code 
# Example variables
x = 5
y = "Hello"
z = [1, 2, 3]

# These will appear in the Variable Inspector

Essential Magic Commands

Magic commands start with % (line magics) or %% (cell magics). Note that available magic commands may vary depending on your Jupyter environment and installed extensions.

Viewing Variables

Code 
# List all variables
%whos

# List just variable names
%who
Variable     Type        Data/Info
----------------------------------
ojs_define   function    <function ojs_define at 0x1a427be20>
x            int         5
y            str         Hello
z            list        n=3
ojs_define   x   y   z

Running Shell Commands

Code 
# Run a shell command
!echo "Hello from the shell!"

# Capture output in a variable
files = !ls
print(files)
Hello from the shell!
['JupyterLab.qmd', 'JupyterLab.quarto_ipynb', 'Pandas_Cheat_Sheet.pdf', 'bar_plots.html', 'bar_plots.qmd', 'chart_customization.qmd', 'comprehensions.qmd', 'control_flows.qmd', 'data_aggregation.html', 'data_aggregation.qmd', 'data_cleaning.html', 'data_cleaning.qmd', 'data_grouping.qmd', 'data_merging.html', 'data_merging.qmd', 'data_selection.qmd', 'dictionaries.html', 'dictionaries.qmd', 'first_steps.html', 'first_steps.ipynb', 'functions.html', 'functions.qmd', 'lists.html', 'lists.qmd', 'matplotlib.html', 'matplotlib.qmd', 'numpy.html', 'numpy.qmd', 'ocean_temperatures.csv', 'output.csv', 'pandas_dataframes.qmd', 'pandas_series.qmd', 'print.html', 'print.qmd', 'random_numbers.qmd', 'read_csv.qmd', 'seaborn.qmd', 'sets.qmd', 'setting_up_python.html', 'setting_up_python.qmd', 'timeseries.html', 'timeseries.qmd', 'workflow_methods.html', 'workflow_methods.qmd']

Useful Keyboard Shortcuts

Action Windows/Linux Mac
Run cell Shift + Enter Shift + Enter
Run cell and insert below Alt + Enter Option + Enter
Run cell and select below Ctrl + Enter Cmd + Enter
Enter command mode Esc Esc
Enter edit mode Enter Enter
Save notebook Ctrl + S Cmd + S
Insert cell above A (in command mode) A (in command mode)
Insert cell below B (in command mode) B (in command mode)
Cut cell X (in command mode) X (in command mode)
Copy cell C (in command mode) C (in command mode)
Paste cell V (in command mode) V (in command mode)
Undo cell action Z (in command mode) Z (in command mode)
Change to code cell Y (in command mode) Y (in command mode)
Change to markdown cell M (in command mode) M (in command mode)
Split cell at cursor Ctrl + Shift + - Cmd + Shift + -
Merge selected cells Shift + M (in command mode) Shift + M (in command mode)
Toggle line numbers Shift + L (in command mode) Shift + L (in command mode)
Toggle output O (in command mode) O (in command mode)

Tips for Beginners

  1. Use Tab for code completion
  2. Add ? after a function name for more detailed help (e.g., print?)
  3. Use dir() to see available attributes/methods (e.g., dir(str))
  4. Use the help() command to get information about functions and objects.

Resources for Further Learning