Python summer course play with python (lab1)

‫‪Play with Python‬‬
‫1‪Lab‬‬
‫كل الشرح في المحاضرة، أي مفاهيم في المعامل :قاعدة هامة‬
‫ستكون مغطاه في المحاضرة قبل المعمل‬
‫المطلوب فقط شرح المطلوب من التمرين‬
‫ودعهم ينطلقون‬

Agenda
• Setup the Environment and Hello World
• Exercise 1:
o Factorial then Factorial with list
• Exercise 2:
o character count and histogram
• Fun:
o Plot!

Setup the Environment
• Install Python 2.7.3:
o python-2.7.3.msi
• Install Aptana IDE:
o Aptana_Studio_3_Setup_3.2.0.exe

Setup the Environment
1- Open your Python IDLE from:
Start >> All Programs >> Python 2.7 >>
IDLE

2- Write your first program:
print "Hello World"
Press Enter

Setup the Environment (Your first project)
3- Start Aptana:
Start >> All Programs >> Aptana Studio 3
press ok for the workspace
4- Create your first project:
Select File >> New >> Project ... >> PyDev Project

5-Enter Project Name: lab1
6-(for first time only) Click on "Please configure an interpreter ... "
7- click auto Config
8- click ok
9- then ok (wait till Aptana finishes ...)
10-create your main file by:
right click on "lab1" in Package Explorer >> New >> PyDev Module
11- Enter Name: main
12- click ok

Python summer course play with python (lab1)

Write the following code in your main file:
n = 5
for i in range(1, n):
print "Hello World"

click on run as from the toolbar

Select "Python Run "

Click Ok (See the run in Console)

put your previous code in a function like this
def main():
n = 5
for i in range(1, n):
print "Hello World"

then call it:
main()

again change your main to return 2 values, "hello world"
string and its length
def main():
s = "Hello World"
return "Hello World", len(s)

then print the return of main like this:
print main()
('Hello World', 11)

Exercise 1
Write this program in your main file:
def count_char(str):
d = {}
for char in str:
if char in d:
d[char] += 1
else:
d[char] = 1
return d
print count_char("My name is FCIS tell me every thing you know
!")

{' ': 9, 'C': 1, 'F': 1, 'I': 2, 'M': 1, 'S': 1, 'a': 1, 'e': 5, 'g': 1, 'i': 2, 'h': 1, 'k': 1, 'm': 2, 'l': 2, 'o': 1,
'n': 3, 's': 1, 'r': 1, 't': 2, 'w': 1, 'v': 1, 'y': 2}
This program counts the occurrences of characters in given string and returns a
dictionary containing for every key character an integer value

Exercise 1 (10 minutes)
Add a new function draw_historgram() that draws an ascii histogram of a given
dictionary (from count_char()) like this:
a : * *
: * * * * * * * * *
e : * * * * *
d : *
g : *
i : * *
M : *
k : *
v : *
m : * * * *
l : * *
o : * *
...

Exercise 1 (Solution)
def draw_historgram(d):
for char in d:
print char, " : ",
for c in range(1, d[char]+1):
print "*",
print ""

Exercise 2
Write this program in your main file:
def fact(n):
if (n <= 1):
return 1
else:
return n * fact(n - 1)

print fact(5)
120

this program computes a factorial for a given integer

Exercise 2 (15 minutes)
Modify this function to make it return the factorial, and also
a list contains all factorials so far like this:

print fact(5)
(120, [1, 2, 6, 24, 120])

the list contains all the factorials from 1 to 5

Exercise 2 (Solution)
def fact(n):
if (n <= 1):
return 1, [1]
else:
prev_fact, theList = fact(n - 1)

current_fact = n* prev_fact
theList.append(current_fact)

return current_fact, theList

print fact(5)

Note: in this exercise the student should be able to implement the solution with the multiple return values ( tuple), this
python feature is explained in the lecture
This exercise is to let the students think the in new way of programming, to feel change from C/C++/C3/Java traditional
languages

Have Fun
Install Pythonxy:
(Click yes for every question the installer asks about
existing python setup)

Open Spyder by:(Start>>python(x,y) >> Spyder >> Spyder
)

Copy and paste your Fact() function to the python
interpreter, and plot Fact() like this:
f, l = fact(5)
plot(l)

Python summer course play with python (lab1)

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