A Crash Course in Python for Scientists

Why Python?

Python is the programming language of choice for many scientists to a large degree because it offers a great deal of power to analyze and model scientific data with relatively little overhead in terms of learning, installation or development time. It is a language you can pick up in a weekend, and use for the rest of one's life.

Please note, is not meant to be a comprehensive overview of Python or programming in general, if you have no programming experience,I suggest to read Python for You and Me.

Topic

Data types
- Numbers
- Strings
- Printing
- Lists
- Dictionaries
- Booleans
- Tuples
- Sets
Comparison Operators
if,elif, else Statements
for Loops
while Loops
range()
list comprehension
map and filter
functions
lambda expressions
map and filter

Data types

Numbers and Arithmetics



In [1]:

    
2 + 2









    Out[1]:





4



In [2]:

    
2 * 3









    Out[2]:





6



In [3]:

    
1 / 2









    Out[3]:





0.5



In [4]:

    
7 // 2









    Out[4]:





3



In [5]:

    
4 ** 3









    Out[5]:





64



In [6]:

    
23 % 4









    Out[6]:





3



In [7]:

    
var = 2 
var2 = 54



In [8]:

    
var3 = var2 - var



In [9]:

    
var3









    Out[9]:





52

String



In [10]:

    
'Hello world'









    Out[10]:





'Hello world'



In [11]:

    
"Hello world"









    Out[11]:





'Hello world'

Print



In [12]:

    
print('Hello world')









    



Hello world



In [13]:

    
name = 'sadegh'
course = 'Machine learning'



In [14]:

    
print('My name is {} this is a {} course'.format(name,course))









    



My name is sadegh this is a Machine learning course



In [15]:

    
print('My name is {myname} this is a {name_course} course'.format(name_course = course, myname = name))









    



My name is sadegh this is a Machine learning course

Lists



In [16]:

    
[1, 2, 3]









    Out[16]:





[1, 2, 3]



In [17]:

    
[1 , [3, 4], 'hello :)']









    Out[17]:





[1, [3, 4], 'hello :)']



In [18]:

    
myList = [1 ,2 ,3, 4, 5, 6]



In [19]:

    
myList.append(12)



In [20]:

    
myList









    Out[20]:





[1, 2, 3, 4, 5, 6, 12]



In [21]:

    
myList[2]









    Out[21]:





3



In [22]:

    
myList[1:3]









    Out[22]:





[2, 3]



In [23]:

    
myList [1:]









    Out[23]:





[2, 3, 4, 5, 6, 12]



In [24]:

    
myList[0:5:2]









    Out[24]:





[1, 3, 5]



In [25]:

    
myList[-1]









    Out[25]:





12



In [26]:

    
myList[0]









    Out[26]:





1



In [27]:

    
myList[0] = 'wow'



In [28]:

    
myList









    Out[28]:





['wow', 2, 3, 4, 5, 6, 12]



In [29]:

    
myList = [[[1, 2 ,3], [4, 5, 6], [7, 8, 9]], [[-1, -2, -3], [-4, -5, -6], [-7, -8 , -9]]]



In [30]:

    
myList[0][2][2]









    Out[30]:





9



In [20]:

    
import numpy as np
np.array(myList)









    Out[20]:





array([ 1,  2,  3,  4,  5,  6, 12])

Dictionaries



In [32]:

    
dictinary = {'key1':'item1','key2':'item2'}



In [33]:

    
dictinary









    Out[33]:





{'key1': 'item1', 'key2': 'item2'}



In [34]:

    
dictinary['key1']









    Out[34]:





'item1'

Tuples



In [35]:

    
t = (1, 2, 3)



In [36]:

    
t[0]









    Out[36]:





1



In [37]:

    
t[0] = 5









    



---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-37-8d3d8637cb4b> in <module>()
----> 1 t[0] = 5

TypeError: 'tuple' object does not support item assignment

Comparison Operators ## Logic Operators

bigger than, les than, equal and ,,,

and, or



In [ ]:

if,elif, else Statements



In [38]:

    
if 23 < 34:
    print('hello')









    



hello



In [39]:

    
if 5 < 2:
    print('first')
else:
    print('second')









    



second



In [40]:

    
if 1 == 2:
    print('first')
elif 3 == 3:
    print('second')
else:
    print('third')









    



second

for Loops



In [41]:

    
seq = ['hello', 'python', 'good']



In [42]:

    
for i in seq:
    print(i)









    



hello
python
good



In [43]:

    
seq = [1, 2, 3, 4, 5]



In [44]:

    
for i in seq:
    print (i ** 2)

range()



In [45]:

    
range(5)









    Out[45]:





range(0, 5)



In [46]:

    
list(range(5))









    Out[46]:





[0, 1, 2, 3, 4]



In [47]:

    
for i in range(2,5):
    print(i)

while Loops



In [48]:

    
i = 1
while i < 5:
    print('number i is: {}'.format(i))
    i += 1









    



number i is: 1
number i is: 2
number i is: 3
number i is: 4

list comprehension



In [49]:

    
x = [1, 2, 3, 4]



In [50]:

    
output = list()
#output = []
for i in x :
    output.append(i + 2)
output









    Out[50]:





[3, 4, 5, 6]



In [51]:

    
[i + 2 for i in x]









    Out[51]:





[3, 4, 5, 6]

functions



In [52]:

    
def func(param1):
    print(param1)



In [53]:

    
func(param1='hello')









    



hello



In [54]:

    
def func2(number):
    return number * 2



In [55]:

    
func2(2)









    Out[55]:





4

map and filter



In [56]:

    
seq = [1,2,3,4,5]



In [57]:

    
map(func2,seq)









    Out[57]:





<map at 0x7fa42815bf60>



In [58]:

    
list(map(func2,seq))









    Out[58]:





[2, 4, 6, 8, 10]

lambda expressions



In [59]:

    
list(map(lambda var: var*2,seq))









    Out[59]:





[2, 4, 6, 8, 10]



In [60]:

    
filter(lambda item: item%2 == 0,seq)









    Out[60]:





<filter at 0x7fa42815bda0>



In [61]:

    
list(filter(lambda item: item%2 == 0,seq))









    Out[61]:





[2, 4]

Other



In [ ]: