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The Jupyter Notebook Interface

The Jupyter Notebook Interface

When a new Jupyter notebook opens, you will see the Jupyter notebook interface. Across the top of the notebook you see the Jupyter icon and the Notebook name. You can click on the notebook name field and change the name of the notebook. Note that the file extension .ipynb is not printed in the file name field, but if you look in the Home tab, you will see that the notebook is saved with the .ipynb extension.

A Jupyter notebook is comprised of a bunch of cells which are arrayed one after another in boxes below the menu items and buttons. There are three main types of cells: code cells, output cells, and markdown cells.

Code Cells

In code cells, you can write Python code, then execute the Python code and see the resulting output. An example of a code cell is shown below.

Jupyter Notebook Code Cell

You can tell you are typing in a code cell because In [ ]: is shown to the left of the cell and the cell-type drop-down menu shows Code.

To run the Python code in a code cell push the [Run] button or type [Shift]+[Enter]. Hitting [Enter] when the cursor is inside a code cell brings the cursor down to a new line.

Jupyter Notebook Run Cell

Output Cells

After a code cell is run, an output cell can be produced below the code cell. The output cell contains the output from the code cell above it. Not all code produces output, so not all code cells produce output cells. The results in output cells can't be edited. If a code cell produces plots, charts or images, these outputs are shown in output cells.

Jupyter Notebook Output Cell

You can clear all the output cells and re-run code cells by selecting [Kernal] --> [Restart Kernal and Clear Output].

Jupyter Notebook Clear All Outputs

Markdown Cells

Markdown cells don't contain Python code. Markdown cells contain text written in Markdown format. Text in markdown cells can be formatted to show bold or italic text. Tables, images, and lists can also be included in markdown cells.

Jupyter Notebook Markdown Cell

Markdown cells are used for documentation and explaining your code. The text in a markdown cell is not executed. Markdown cells can be formatted with a few special characters.

Markdown cells are run like code cells. The difference is that when markdown cells are run, the text is formatted (when code cells run, code is executed). Markdown cells are run by clicking the [Run] button or by pressing [Shift] + [Enter]

Text in markdown cells can be formatted using markdown syntax. An example of markdown syntax is putting an underscore before and after a word to cause the word to be formatted in italics.

Headings

Headings are created in markdown cells using the hash symbol #. One # is the largest heading. Four hashes #### is the smallest heading.

# H1 Heading
## H2 Heading
### H3 Heading
#### H4 Heading

Code Blocks

Code blocks can be inserted in Jupyter notebook markdown cells. For inline code blocks use the ` left quote character, the character to the left of the number [1]``` and above ```[Tab] on most keyboards.

This is inline code: ` ` ` Inline code block ` ` ` within a paragraph

For a separated code block use three ` left quote characters on one line, followed by the code block on separate lines. Terminate the separate code block with a line of three ` left quote characters.

```

Separated code block

```

Bold and italics

Bold and italic font is displayed by surrounding text with a double asterisk for **bold** and a single underscore for _italics_

**bold** produces bold

_italics_ produces italics

**_bold and italic_** produces bold and italic

Tables

Tables are displayed using the pipe | character, which is [Shift]+[\] on most keyboards. Columns are separated by pipes | and rows are separated by lines. After the header row, a row of pipes and dashes --- are needed to define the table.

| header1 | header 2 | header 3 |
| --- | --- | --- |
| col 1 | col 2 | col 3 |
| col 1 | col 2 | col 3 |

produces:

header1 header 2 header 3
col 1 col 2 col 3
col 1 col 2 col 3

Bullet Points and Lists

Bullet points are produced using the asterisk character *

 * item 1
 * item 2
 * item 3

produces

  • item 1
  • item 2

Numbered lists are produced using sequential numbers followed by a dot. Indent sub-items with two spaces.

1. First item
2. Second item
3. Third item
  1. sub item
  2. sub item
    1. sub-sub item
    2. sub-sub item

produces

  1. First item
  2. Second item
  3. Third item
  4. sub item
  5. sub item
    1. sub-sub item
    2. sub-sub item

Horizontal Rule

A horizontal rule is specified with three asterisks *** on a single line.

***

produces


Hyperlinks are specified using a set of square brackets [ ] followed by a pair of parenthesis ( ) The text inside the square brackets will be the link, the link address goes in the parenthesis.

[Python.org](https://python.org/)

produces

Python.org

Images

Images are embedded in Jupyter Notebook markdown using the exclamation point and square brackets ![ ], followed by the image file path in parenthesis ( ). If the image can not be displayed, the text in square brackets will be shown. The image can be in the same directory as the notebook, or a relative path can be specified. In this case, the image engineering.png is stored in the images directory, which is a subdirectory of the directory the notebook is saved in.

![Engineering Image](images/engineering.png)

produces

Image displayed in a Jupyter notebook markdown cell

LaTeX Math

LaTeX Math equations and symbols are rendered by markdown cells. A more extensive list of LaTeX commands can be found in the appendix.

$$ \int_{a}^{b} \frac{1}{x^2} dx $$

produces

\int_{a}^{b} \frac{1}{x^2} dx

html

Because Jupyter notebooks are rendered by web browsers, just about any HTML tag can be included in the markdown portion of a notebook. An example of an HTML tag is the <sup> </sup> tags that surround superscript text.

x<sup>2</sup>

produces

x2

Text can be colored using html <font> </font> tags

<font color=red>Red Text</font>

produces

Red Text

warning boxes

bootstrap style warning boxes can be included in Jupyter notebook markdown using <div> tags

<div class="alert alert-danger" role="alert">
  <strong>Warning!</strong> Python lists start at 0
</div>

produces

Creating a new cell

You can create a new cell in a Jupyter Notebook by clicking the [+] button in the upper menu. Clicking the [+] button produces a new code cell below the currently active cell.

Jupyter Notebook New Cell Button

You can also create a new cell using Insert --> Insert Cell Above or Insert Cell Below. You can choose to insert a cell above or below the currently active cell.

Changing the cell type

The type of cell: code cell or markdown cell, is changed by clicking on a cell and selecting the cell type from the drop-down menu. Typing [Esc] + [m] changes the cell type to a markdown cell. Typing [Esc] + [y] changes the cell type to a code cell.

Jupyter Notebook Change Cell Type

Saving a Jupyter Notebook

Jupyter notebooks can be saved using the save icon in the upper menu or by pressing [Ctrl] + [s].

Jupyter Notebook Save

Jupyter notebooks can also be saved as a copy, similar to the Save As command common in many programs. To save a copy of a Jupyter notebook use File --> Make a Copy...

Jupyter Notebook save a copy

Renaming a Jupyter Notebook

Jupyter notebooks are renamed by clicking on the notebook name above the upper menu and typing a new name into the dialog box.

Jupyter Notebook rename notebook

Jupyter Notebook rename dialog box

Downloading a Jupyter Notebook

Jupyter notebooks can be downloaded and saved using File --> Download As --> Notebook (.ipynb). Selecting this menu option will download the notebook as a .ipynb file.

Jupyter Notebook downloaded as .ipynb file

Note that when a .ipynb file is viewed in a text editor like notepad, the notebook is unformatted and looks like a confusing jumble of text. The notebook needs to be opened in a Jupyter notebook file browser in order for the code in the notebook to run and the markdown text to render.

Jupyter Notebook JSON in notepad

Saving Jupyter Notebooks in Other Formats

Jupyter notebooks can be saved in other formats besides the native .ipynb format. These formats can be accessed using the [File] --> [Download As] menu.

Jupyter Notebook Export Options

The available file download types are:

  • Notebook (.ipynb) - The native jupyter notebook format
  • Python (.py) - The native Python code file type.
  • HTML (.html) - A web page
  • Markdown (.md) - Markdown format
  • reST (.rst) - Restructured text format
  • LaTeX (.tex) - LaTeX Article format
  • PDF via LaTeX - a pdf exported from LeTeX, requires a converter

When a Notebook is saved as a .py file, all text in markdown cells is converted to comments, and any code cells stay intact as Python code.

Markdown Cells as comments seen in a downloaded .py file