Working environment
====================

During this course we will work on Window's computers which have Python 3. installed via the Anaconda distribution and Python 2.7. installed together with the ArcGIS-software.
There are different options of how to run Python code. We will start with using Python trough the Spyder IDE while learning the basics of Python. Later in the week we will
swhitch to python 2.7. in order to run ArcGIS processes trough Python.

In addition to the different Python-interfaces we will be using,it is also useful to be familiar
with basic `command line functions <#Using the command line>`__ in the Windows Command Prompt.

What is an integrated development environment?
----------------------------------------------

An *integrated development environment* or *IDE* is a software program
or package that provides a set of tools for writing, testing, and
debugging software in a convenient, practical interface (often a single
window). Often, the components in the IDE include a text editor with
options to help debug source code, a built-in terminal or console
window, and a pane for viewing variable values, documentation or
browsing files on the computer. For us, the main reason for introducing
an IDE is that it makes it easier and faster to write and test Python
scripts, and common mistakes that can be made when writing code can be
indicated in the IDE text editor to help you fix thinks more easily. We
will be using the `Spyder IDE <https://pythonhosted.org/spyder/>`__
that is included with
`Anaconda <https://www.continuum.io/anaconda-overview>`__, but it is
just one of `many Python
IDEs <https://wiki.python.org/moin/IntegratedDevelopmentEnvironments>`__.

Spyder IDE
-----------

If you haven't done so already, open **Spyder** from All Programs > Anaconda3 > Spyder

Also, for this demonstration we will be using the Python script file
`Spyder-demo-script.py <https://raw.githubusercontent.com/Python-for-geo-people/Lesson-4-Functions-Modules/master/src/Spyder-demo-script.py>`__. Download the file from GitHub to your computer.


An overview of the Spyder IDE
-----------------------------

.. figure:: /img/Spyder.png
   :alt: Spyder

   Spyder IDE

We will be using the **Spyder** IDE in the basic exercises of this course.
As mentioned above, this will allow us to more easily create and edit Python scripts,
as well as provide some helpful tools for continuing to learn programming in Python and resolve common
code bugs. The Spyder IDE window is broken into
several different panes, labeled in the figure below. We will briefly
look at each in the following sections.

.. figure:: /img/Spyder-annotated.png
   :alt: Spyder components

   Panes in the Spyder IDE window

**The editor pane**

The main pane on the left is the editor pane, used for writing Python
scripts. If you have already loaded the
`Spyder-demo-script.py <https://raw.githubusercontent.com/Python-for-geo-people/Lesson-4-Functions-Modules/master/src/Spyder-demo-script.py>`__ file, you
will see it is basically a normal text editor window with colors used to
highlight the text in the script. In addition, you can see line numbers
on the left side, which can be helpful when debugging.

There are several features that make the **Spyder** editor pane more
useful than a standard text editor:

1. A popup window will appear when you type in functions, providing a
   bit of documentation about using them. For example, when you type in
   the print statement, a window will pop up after you have typed
   ``print(``, showing you how to use the function.

2. If you have a syntax error on a line of your program, a small yellow
   triangle or red octagon will be displayed to the left of that line.
   Hovering over the triangle (or octagon) with your mouse will provide
   some additional information about the possible cause of the error.

3. Within **Spyder** you can easily run your Python scripts by either
   clicking on the green play icon in the set of icons at the top of the
   window, or by going to **Run** -> **Run** in the menu bar.

**The explorer pane**

The explorer pane in **Spyder** serves three purposes:

1. *Providing documentation on demand for objects used in your Python
   scripts or in the IPython console*. The **Object inspector** tab can
   be used to load documentation of various functions or other objects
   used either in a script in the editor pane or the IPython console at
   the bottom right. Use is simple, just click on the name of a function
   in either location and press **Ctrl-i** to load the documentation. If
   you have it loaded you can try this with the ``bin()`` function on
   line 30 of the
   `Spyder-demo-script.py <https://raw.githubusercontent.com/Python-for-geo-people/Lesson-4-Functions-Modules/master/src/Spyder-demo-script.py>`__ file,
   for example.

2. *Listing information about variables in memory*. If you have defined
   any variables in the IPython console or have run a script in the
   editor pane, you can find information about defined variables in
   memory listed in the **Variable explorer** tab. If you run the
   `Spyder-demo-script.py <https://raw.githubusercontent.com/Python-for-geo-people/Lesson-4-Functions-Modules/master/src/Spyder-demo-script.py>`__ script,
   for example, you will see that the initial value of variable
   ``BigNumber`` is modified within the script, but kept in the
   definition of the list ``OddList``.

3. *Allowing you to browse the filesystem within **Spyder***. Lastly,
   you can browse files on your computer using the **File explorer**
   tab. In future lessons and exercises you may find this helpful for
   locating data files, for example.

**The console pane**

The console pane is mainly useful because it provides an IPython console
for your use. It is a normal IPython console, but note that similar to
the editor pane, popup windows will appear when typing in functions to
display brief documentation snippets.

The other item that can be displayed in the console pane is your history
of commands entered in the IPython console. This is obviously quite
helpful if you're testing things in the IPython console before copying
them to a script in the editor pane. You can view the history pane by
going to **View** -> **Panes** -> **History log** in the menu bar.



Using the command line
----------------------

It is good to be familiar with the basics in navigating and using the Disk Operating System (DOS) from  a command line. Open command prompt window by typing `cmd` to Windows search in the start menu.

Here are some quick tips on how to navigate in Windows Command line, which are needed in this course:


+-----------------+-------------------------------------------+
| Command         | Result                                    |
+=================+===========================================+
| ``C:``          | Move to C:-drive                          |
+-----------------+-------------------------------------------+
| ``cd folder``   | move to folder in current directory       |
+-----------------+-------------------------------------------+
| ``cd..``        | move to parent directory                  |
+-----------------+-------------------------------------------+
|``cd C:/temp``   | move to directory C:/temp                 |
+-----------------+-------------------------------------------+
| ``dir``         | lists contents of the current directory   |
+-----------------+-------------------------------------------+


**Keyboard shortcuts**

- Ctrl+C stop ongoing process

- Use up and down arrows for calling previous commands

- Use copy/paste with long file paths!



.. figure:: /img/cmd.png
   :alt: Command prompt

   Windows command line