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Installing PIP for Python

without comments

If you’re on a Mac running macOS Sierra, you can install PIP to add packages. PIP stands for either of the following:

  • PIP installs Packages
  • PIP installs Python

You use the following to install the PIP utility:

sudo easy_install pip

It should return the following:

Searching for pip
Reading https://pypi.python.org/simple/pip/
Best match: pip 9.0.1
Downloading https://pypi.python.org/packages/11/b6/abcb525026a4be042b486df43905d6893fb04f05aac21c32c638e939e447/pip-9.0.1.tar.gz#md5=35f01da33009719497f01a4ba69d63c9
Processing pip-9.0.1.tar.gz
Writing /tmp/easy_install-ryxjDg/pip-9.0.1/setup.cfg
Running pip-9.0.1/setup.py -q bdist_egg --dist-dir /tmp/easy_install-ryxjDg/pip-9.0.1/egg-dist-tmp-l6_Jjt
/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/dist.py:267: UserWarning: Unknown distribution option: 'python_requires'
  warnings.warn(msg)
warning: no previously-included files found matching '.coveragerc'
warning: no previously-included files found matching '.mailmap'
warning: no previously-included files found matching '.travis.yml'
warning: no previously-included files found matching '.landscape.yml'
warning: no previously-included files found matching 'pip/_vendor/Makefile'
warning: no previously-included files found matching 'tox.ini'
warning: no previously-included files found matching 'dev-requirements.txt'
warning: no previously-included files found matching 'appveyor.yml'
no previously-included directories found matching '.github'
no previously-included directories found matching '.travis'
no previously-included directories found matching 'docs/_build'
no previously-included directories found matching 'contrib'
no previously-included directories found matching 'tasks'
no previously-included directories found matching 'tests'
creating /Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg
Extracting pip-9.0.1-py2.7.egg to /Library/Python/2.7/site-packages
Adding pip 9.0.1 to easy-install.pth file
Installing pip script to /usr/local/bin
Installing pip2.7 script to /usr/local/bin
Installing pip2 script to /usr/local/bin
 
Installed /Library/Python/2.7/site-packages/pip-9.0.1-py2.7.egg
Processing dependencies for pip
Finished processing dependencies for pip

After you install PIP, you can use PIP to add custom packages to the Python environment. The

sudo pip install easygui

You get the following warning and installation:

The directory '/Users/michaelmclaughlin/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/Users/michaelmclaughlin/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting easygui
  Downloading easygui-0.98.1-py2.py3-none-any.whl (90kB)
    100% |████████████████████████████████| 92kB 1.0MB/s 
Installing collected packages: easygui
Successfully installed easygui-0.98.1

After installing the easygui Python library, you can change to the root directory to confirm the installation of the easygui Python library with the following command:

find . -name easygui* 2>/dev/null

It returns the following:

./Library/Python/2.7/site-packages/easygui
./Library/Python/2.7/site-packages/easygui/easygui.py
./Library/Python/2.7/site-packages/easygui/easygui.pyc
./Library/Python/2.7/site-packages/easygui-0.98.1.dist-info

You can connect to Python 2.7 in a Terminal session. Then, you use the easygui library to run a Hello World! message box with the following commands in the Python shell:

import easygui
easy gui.msgbox("Hello World!")

It will raise the following image:

Hopefully, this helps a few folks.

Written by maclochlainn

May 2nd, 2017 at 12:51 am

Python variable not defined

without comments

While working with a programming example for my students, I ran into an interesting run-time error when I changed their approach to importing Python’s random module. Here’s the raised error message:

Traceback (most recent call last):
  File "windowBouncingBalls.py", line 84, in <module>
    speed = [choice([-2,2]), choice([-2,2])]
NameError: name 'choice' is not defined

You raise the missing choice identifier when two things occur. The first thing requires you to use a standard import statement, like the following example, and the second thing requires you to continue to reference the identifier as “choice“.

import random

You can avoid the error by making the import of random like this:

from random import *

Or, you can leave the ordinary import statement and fully qualify the choice identifier with the random module name, like this:

    speed = [random.choice([-2,2]), random.choice([-2,2])]

As always, I hope this helps those who encounter a similar problem.

Written by maclochlainn

March 27th, 2017 at 12:23 am

Install PyGame on Fedora

without comments

The PyGame library is a wonderful tool for building games with Python. It lets you accomplish a great deal by simply managing events. You need to understand how to use Python functions, modules, and events to build games with this Python library.

You can download and install the PyGame library with the yum utility like this:

yum install -y pygame

It should generate the following list when you install it as the root user:

Loaded plugins: langpacks, refresh-packagekit
Available Packages
pygame.x86_64                        1.9.1-14.fc20                        fedora
[root@localhost ~]# yum install -y pygame
Loaded plugins: langpacks, refresh-packagekit
Resolving Dependencies
--> Running transaction check
---> Package pygame.x86_64 0:1.9.1-14.fc20 will be installed
--> Processing Dependency: numpy for package: pygame-1.9.1-14.fc20.x86_64
--> Processing Dependency: libportmidi.so.0()(64bit) for package: pygame-1.9.1-14.fc20.x86_64
--> Processing Dependency: libSDL_ttf-2.0.so.0()(64bit) for package: pygame-1.9.1-14.fc20.x86_64
--> Processing Dependency: libSDL_mixer-1.2.so.0()(64bit) for package: pygame-1.9.1-14.fc20.x86_64
--> Processing Dependency: libSDL_image-1.2.so.0()(64bit) for package: pygame-1.9.1-14.fc20.x86_64
--> Running transaction check
---> Package SDL_image.x86_64 0:1.2.12-7.fc20 will be installed
---> Package SDL_mixer.x86_64 0:1.2.12-5.fc20 will be installed
--> Processing Dependency: libmikmod for package: SDL_mixer-1.2.12-5.fc20.x86_64
---> Package SDL_ttf.x86_64 0:2.0.11-4.fc20 will be installed
---> Package numpy.x86_64 1:1.8.2-2.fc20 will be installed
--> Processing Dependency: python-nose for package: 1:numpy-1.8.2-2.fc20.x86_64
---> Package portmidi.x86_64 0:217-9.fc20 will be installed
--> Running transaction check
---> Package libmikmod.x86_64 0:3.3.6-3.fc20 will be installed
---> Package python-nose.noarch 0:1.3.0-1.fc20 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package            Arch          Version                  Repository      Size
================================================================================
Installing:
 pygame             x86_64        1.9.1-14.fc20            fedora         2.1 M
Installing for dependencies:
 SDL_image          x86_64        1.2.12-7.fc20            fedora          41 k
 SDL_mixer          x86_64        1.2.12-5.fc20            fedora          91 k
 SDL_ttf            x86_64        2.0.11-4.fc20            fedora          22 k
 libmikmod          x86_64        3.3.6-3.fc20             updates        142 k
 numpy              x86_64        1:1.8.2-2.fc20           updates        3.0 M
 portmidi           x86_64        217-9.fc20               fedora          26 k
 python-nose        noarch        1.3.0-1.fc20             fedora         272 k
 
Transaction Summary
================================================================================
Install  1 Package (+7 Dependent packages)
 
Total download size: 5.7 M
Installed size: 21 M
Downloading packages:
(1/8): SDL_image-1.2.12-7.fc20.x86_64.rpm                   |  41 kB  00:00     
(2/8): SDL_mixer-1.2.12-5.fc20.x86_64.rpm                   |  91 kB  00:00     
(3/8): portmidi-217-9.fc20.x86_64.rpm                       |  26 kB  00:00     
(4/8): SDL_ttf-2.0.11-4.fc20.x86_64.rpm                     |  22 kB  00:00     
(5/8): libmikmod-3.3.6-3.fc20.x86_64.rpm                    | 142 kB  00:00     
(6/8): numpy-1.8.2-2.fc20.x86_64.rpm                        | 3.0 MB  00:02     
(7/8): pygame-1.9.1-14.fc20.x86_64.rpm                      | 2.1 MB  00:01     
(8/8): python-nose-1.3.0-1.fc20.noarch.rpm                  | 272 kB  00:00     
--------------------------------------------------------------------------------
Total                                              1.7 MB/s | 5.7 MB  00:03     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : SDL_ttf-2.0.11-4.fc20.x86_64                                 1/8 
  Installing : SDL_image-1.2.12-7.fc20.x86_64                               2/8 
  Installing : portmidi-217-9.fc20.x86_64                                   3/8 
  Installing : libmikmod-3.3.6-3.fc20.x86_64                                4/8 
  Installing : SDL_mixer-1.2.12-5.fc20.x86_64                               5/8 
  Installing : python-nose-1.3.0-1.fc20.noarch                              6/8 
  Installing : 1:numpy-1.8.2-2.fc20.x86_64                                  7/8 
  Installing : pygame-1.9.1-14.fc20.x86_64                                  8/8 
  Verifying  : pygame-1.9.1-14.fc20.x86_64                                  1/8 
  Verifying  : SDL_mixer-1.2.12-5.fc20.x86_64                               2/8 
  Verifying  : python-nose-1.3.0-1.fc20.noarch                              3/8 
  Verifying  : libmikmod-3.3.6-3.fc20.x86_64                                4/8 
  Verifying  : 1:numpy-1.8.2-2.fc20.x86_64                                  5/8 
  Verifying  : portmidi-217-9.fc20.x86_64                                   6/8 
  Verifying  : SDL_image-1.2.12-7.fc20.x86_64                               7/8 
  Verifying  : SDL_ttf-2.0.11-4.fc20.x86_64                                 8/8 
 
Installed:
  pygame.x86_64 0:1.9.1-14.fc20                                                 
 
Dependency Installed:
  SDL_image.x86_64 0:1.2.12-7.fc20        SDL_mixer.x86_64 0:1.2.12-5.fc20      
  SDL_ttf.x86_64 0:2.0.11-4.fc20          libmikmod.x86_64 0:3.3.6-3.fc20       
  numpy.x86_64 1:1.8.2-2.fc20             portmidi.x86_64 0:217-9.fc20          
  python-nose.noarch 0:1.3.0-1.fc20      
 
Complete!

I hope this helps folks install the software.

Written by maclochlainn

March 25th, 2017 at 1:49 am

Install EasyGUI on Fedora

without comments

The EasyGUI library is a nice tool for developing GUI applications. It doesn’t require you to know event-driven programming to write basic GUI applications because it’s based on Python functions.

You can download and install the EasyGUI library with yum utility like this:

yum install -y python-easygui

It should generate the following list:

Loaded plugins: langpacks, refresh-packagekit
mysql-connectors-community                                  | 2.5 kB  00:00     
mysql-tools-community                                       | 2.5 kB  00:00     
mysql56-community                                           | 2.5 kB  00:00     
pgdg93                                                      | 3.6 kB  00:00     
updates/20/x86_64/metalink                                  | 2.8 kB  00:00     
Resolving Dependencies
--> Running transaction check
---> Package python-easygui.noarch 0:0.96-7.fc20 will be installed
--> Processing Dependency: tkinter for package: python-easygui-0.96-7.fc20.noarch
--> Processing Dependency: python-setuptools for package: python-easygui-0.96-7.fc20.noarch
--> Running transaction check
---> Package python-setuptools.noarch 0:1.4.2-1.fc20 will be installed
---> Package tkinter.x86_64 0:2.7.5-16.fc20 will be installed
--> Processing Dependency: libtk8.5.so()(64bit) for package: tkinter-2.7.5-16.fc20.x86_64
--> Processing Dependency: libtcl8.5.so()(64bit) for package: tkinter-2.7.5-16.fc20.x86_64
--> Processing Dependency: libTix.so()(64bit) for package: tkinter-2.7.5-16.fc20.x86_64
--> Running transaction check
---> Package tcl.x86_64 1:8.5.14-1.fc20 will be installed
---> Package tix.x86_64 1:8.4.3-11.fc20 will be installed
---> Package tk.x86_64 1:8.5.14-1.fc20 will be installed
--> Finished Dependency Resolution
 
Dependencies Resolved
 
================================================================================
 Package                 Arch         Version               Repository     Size
================================================================================
Installing:
 python-easygui          noarch       0.96-7.fc20           fedora        481 k
Installing for dependencies:
 python-setuptools       noarch       1.4.2-1.fc20          updates       413 k
 tcl                     x86_64       1:8.5.14-1.fc20       fedora        1.9 M
 tix                     x86_64       1:8.4.3-11.fc20       fedora        253 k
 tk                      x86_64       1:8.5.14-1.fc20       fedora        1.4 M
 tkinter                 x86_64       2.7.5-16.fc20         updates       316 k
 
Transaction Summary
================================================================================
Install  1 Package (+5 Dependent packages)
 
Total download size: 4.7 M
Installed size: 13 M
Downloading packages:
(1/6): python-setuptools-1.4.2-1.fc20.noarch.rpm            | 413 kB  00:00     
(2/6): python-easygui-0.96-7.fc20.noarch.rpm                | 481 kB  00:00     
(3/6): tkinter-2.7.5-16.fc20.x86_64.rpm                     | 316 kB  00:00     
(4/6): tix-8.4.3-11.fc20.x86_64.rpm                         | 253 kB  00:01     
(5/6): tcl-8.5.14-1.fc20.x86_64.rpm                         | 1.9 MB  00:01     
(6/6): tk-8.5.14-1.fc20.x86_64.rpm                          | 1.4 MB  00:03     
--------------------------------------------------------------------------------
Total                                              1.5 MB/s | 4.7 MB  00:03     
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction (shutdown inhibited)
  Installing : 1:tcl-8.5.14-1.fc20.x86_64                                   1/6 
  Installing : 1:tk-8.5.14-1.fc20.x86_64                                    2/6 
  Installing : 1:tix-8.4.3-11.fc20.x86_64                                   3/6 
  Installing : tkinter-2.7.5-16.fc20.x86_64                                 4/6 
  Installing : python-setuptools-1.4.2-1.fc20.noarch                        5/6 
  Installing : python-easygui-0.96-7.fc20.noarch                            6/6 
  Verifying  : 1:tk-8.5.14-1.fc20.x86_64                                    1/6 
  Verifying  : tkinter-2.7.5-16.fc20.x86_64                                 2/6 
  Verifying  : 1:tix-8.4.3-11.fc20.x86_64                                   3/6 
  Verifying  : 1:tcl-8.5.14-1.fc20.x86_64                                   4/6 
  Verifying  : python-easygui-0.96-7.fc20.noarch                            5/6 
  Verifying  : python-setuptools-1.4.2-1.fc20.noarch                        6/6 
 
Installed:
  python-easygui.noarch 0:0.96-7.fc20                                           
 
Dependency Installed:
  python-setuptools.noarch 0:1.4.2-1.fc20       tcl.x86_64 1:8.5.14-1.fc20      
  tix.x86_64 1:8.4.3-11.fc20                    tk.x86_64 1:8.5.14-1.fc20       
  tkinter.x86_64 0:2.7.5-16.fc20               
 
Complete!

You can then test the EasyGUI library with the following three lines of code inside the IDLE interpreter:

Python 2.7.5 (default, Apr 10 2015, 08:09:05) 
[GCC 4.8.3 20140911 (Red Hat 4.8.3-7)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import easygui
>>> flavor = easygui.enterbox("What flavor of bum do you like?")
>>> if easygui.msgbox("You like " + flavor + " gum.") == 'OK':
...   print "OK button clicked ..."
... 
OK button clicked ...

The easygui.enterbox call displays the image below. Enter “Peppermint” in the entry box and click the OK button to assign the “Peppermint” string literal to the flavor variable.

The easygui.msgbox call displays the message below:

When you click the OK button, the program returns an “OK” string to the Python code. It prints the string “OK button clicked …” string:

As always, I hope this helps those looking for instructions and a quick way to play with Python and GUI applications.

Written by maclochlainn

February 22nd, 2017 at 1:35 am

Basic Python Object

with one comment

One of my students wanted a quick example of a Python object with getters and setters. So, I wrote a little example that I’ll share.

You define this file in a physical directory that is in your $PYTHONPATH, like this:

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# Define Coordinate class.
class Coordinate:
  # The method that initializes the Coordinate class.
  def __init__ (self, x, y):
    self.x = x
    self.y = y
 
  # Gets the x value from the instance.
  def getX (self):
    return self.x
 
  # Gets the y value from the instance.
  def getY (self):
    return self.y
 
  # Sets the x value in the instance.
  def setX (self, x):
    self.x = x
 
  # Sets the y value in the instance.    
  def setY (self, y):
    self.y = y
 
  # Prints the coordinate pair.
  def printCoordinate(self):
    print (self.x, self.y)

Assuming the file name is Coordinate.py, you can put it into the Python Idle environment with the following command:

from Coordinate import Coordinate

You initialize the class, like this:

g = Coordinate(49,49)

Then, you can access the variables of the class or it’s methods as shown below:

# Print the retrieved value of x from the g instance of the Coordinate class.
print g.getX()
 
# Print the formatted and retrieved value of x from the g instance of the Coordinate class.
print "[" + str(g.getX()) + "]"
 
# Set the value of x inside the g instance of the Coordinate class.
print g.setX(39)
 
# Print the Coordinates as a set.
g.printCoordinate()

You would see the following results:

49
[49]
(39,49)

As always, I hope that helps those looking for a solution.

Written by maclochlainn

October 30th, 2016 at 6:23 pm

Create a Python Module

without comments

Sometime formal programming documentation is less than clear. At least, it’s less than clear until you’ve written your first solution. The Modules section of the Python language is one of those that takes a few moments to digest.

Chapters 22 and 23 in Learning Python gives some additional details but not a clear step-by-step approach to implementing Python modules. This post is designed to present the steps to write, import, and call a Python module. I figured that it would be helpful to write one for my students, and posting it in the blog seemed like the best idea.

I wrote the module to parse an Oracle version string into what we’d commonly expect to see, like the release number, an “R”, a release version, and then the full version number. The module name is more or less equivalent to a package name, and the file name is effectively the module name. The file name is strVersionOracle.py, which makes the strVersionOracle the module name.

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# Parse and format Oracle version.
def formatVersion(s):
 
  # Split string into collection.
  list = s.split(".")
 
  # Iterate through the result set.
  for i, l in enumerate(list):
    if i == 0 and list[i] == "11":
      label = str(l) + "g"
    elif i == 0 and list[i] == "12":
      label = label + str(l) + "c"
    elif i == 1:
      label = label + "R" + list[i] + " (" + s + ")"
 
  # Return the formatted string.
  return label

You can put this in any directory as long as you add it to the Python path. There are two Python paths to maintain. One is in the file system and the other is in Python’s interactive IDLE environment. You can check the contents of the IDLE path with the following interactive commands:

import sys
print sys.path

It prints the following:

['', '/usr/lib64/python27.zip', '/usr/lib64/python2.7', '/usr/lib64/python2.7/plat-linux2', '/usr/lib64/python2.7/lib-tk', '/usr/lib64/python2.7/lib-old', '/usr/lib64/python2.7/lib-dynload', '/usr/lib64/python2.7/site-packages', '/usr/lib64/python2.7/site-packages/gtk-2.0', '/usr/lib/python2.7/site-packages']

You can append to the IDLE path using the following command:

sys.path.append("/home/student/Code/python")

After putting the module in the runtime path, you can test the code in the IDLE environment:

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import cx_Oracle
db = cx_Oracle.connect("student/student@xe")
print strVersionOracle.formatVersion(db.version)

Line 3 prints the result by calling the formatVersion function inside the strVersionOracle module. It prints the following:

11gR2 (11.2.0.2.0)

You can test the program outside of the runtime environment with the following oracleConnection.py file. It runs

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# Import the Oracle library.
import cx_Oracle
import strVersionOracle
 
try:
  # Create a connection.
  db = cx_Oracle.connect("student/student@xe")
 
  # Print a message.
  print "Connected to the Oracle " + strVersionOracle.formatVersion(db.version) + " database."
 
except cx_Oracle.DatabaseError, e:
  error, = e.args
  print >> sys.stderr, "Oracle-Error-Code:", error.code
  print >> sys.stderr, "Oracle-Error-Message:", error.message
 
finally:
  # Close connection. 
  db.close()

You can call the formatVersion() function rather than a combination of module and function names when you write a more qualified import statement on line 3, like:

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from strVersionOracle import formatVersion

Then, you can call the formatVersion() function like this on line 10:

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  print "Connected to the Oracle " + formatVersion(db.version) + " database."

It works because you told it to import a function from a Python module. The first example imports a module that may contain one to many functions, and that style requires you to qualify the location of functions inside imported modules.

The oracleConnection.py program works when you call it from the Bash shell provided you do so from the same directory where the oracleConnection.py and strVersionOracle.py files (or Python modules) are located. If you call the oracleConnection.py file from a different directory, the reference to the library raises the following error:

Traceback (most recent call last):
  File "oracleConnection.py", line 3, in <module>
    import strVersionOracle
ImportError: No module named strVersionOracle

You can fix this error by adding the directory where the strVersionOracle.py file exists, like

export set PYTHONPATH=/home/student/Code/python

Then, you can call successfully the oracleConnection.py file from any directory:

python oracleConnection.py

The program will connect to the Oracle database as the student user, and print the following message to the console:

Connected to the Oracle 11gR2 (11.2.0.2.0) database.

I hope this helps those trying to create and use Python modules.

Written by maclochlainn

October 19th, 2016 at 11:50 pm

Python for loops

without comments

It’s always interesting to explain a new programming language to students. Python does presents some challenges to that learning process. I think for-loops can be a bit of a challenge until you understand them. Many students are most familiar with the traditional for loop like Java:

for (i = 0; i < 5; i++) { ... }

Python supports three types of for-loops – a range for loop, a for-each expression, and a for-loop with enumeration. Below are examples of each of these loops.

  1. A range for-loop goes from a low numerical value to a high numerical value, like:
  2. for i in range(0,3):
      print i

    It prints the following range values:

    0
    1
    2
  1. A for-each loop goes from the first to the last item while ignoring indexes, like:
  2. list = ['a','b','c']
    for i in list:
      print i

    It prints the following elements of the list:

    a
    b
    c
  1. A for-loop with enumeration goes from the first to the last item while ignoring indexes, like:
  2. list = ['a','b','c']
      for i, e in enumerate(list):
        print "[" + str(i) + "][" + list[i] + "]"

    The i represents the index values and the e represents the elements of a list. The str() function casts the numeric value to a string.

    It prints the following:

    [0][a]
    [1][b]
    [2][c]

This should help my students and I hope it helps you if you’re trying to sort out how to use for loops in Python.

Written by maclochlainn

October 19th, 2016 at 9:02 pm