Python is a great general-purpose programming language on its own, but with the help of a few popular libraries (numpy, scipy, matplotlib) it becomes a powerful environment for scientific computing.
This tutorial will serve as a quick crash course both on the Python programming language. We will be using the latest verion of Python, 3.6.
Part I will cover:
Python is a high-level, dynamically typed programming language. Python has an expressive and readable syntax.
There are only three number types in Python: integers, floats and complex numbers.
x = 3
y = 2.5
z = 2 + 4j
print(type(x))
print(type(y))
print(type(z))
print(4 + 1)
print(10 - 5)
print(4 * 2)
print(3 ** 2) # exponentiation
print(3 / 2) # division
print(3 // 2) # floor division
a = 4
b = 5
a += 1
b *= 3
print(a, b)
Python does not have unary increment (x++) or decrement (x--) operators.
Python uses English words for Boolean logic.
t = True
f = False
print(type(t))
print(f)
Here are the basic logical operations.
print(t and f)
print(t or f)
print(not t)
x = 5
if x % 2 == 0 or x > 0:
print('x is even or positive')
print("still in this block")
print("different block")
String literals can use single, double or triple quotes.
str1 = 'hello'
str2 = "world"
str3 = '''hello, world''' # or """hello, world!"""
print(str1, len(str2))
print(str3)
s = str1 + ', ' + str2
print(s)
formatter = 'Hello {}, did you get the {} tests?'.format('Mike',7)
print(formatter)
String objects have many useful methods; for example:
s = "hello"
print(s.capitalize()) # Capitalize a string; prints "Hello"
print(s.upper()) # Convert a string to uppercase; prints "HELLO"
print(s.replace('l', '(ell)')) # Replace all instances of one substring with another;
# prints "he(ell)(ell)o"
print('I am ' + str(16) + ' years old') # must cast numbers to string(str)
x = "hello, world"
print(x[0])
print(x[2]) # With slicing(see below), we can extract substrings.
A substring can be extracted by creating a slice of the original string.
greeting = "Hi! How are you?"
greeting
# strings can be indexed [start, stop)
greeting[0:2] # notice index starts with 0
# +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---
# | H | i | ! | | H | o | w | | a | r | e | | y | o | u | ?
# +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---
# 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
# -16 -15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1
greeting[12:-1]
x = "string"
print(x[1:4]) # substring beginning from 1 to 4(not including)
print(x[:]) # the entire string
print(x[2:]) # from 2 to end
y = 'programming'
print(y[1:7:2]) # from 1 to 7(not including) every other character(by 2)
You can find a list of all string methods in the documentation.
var = 100
if var == 100:
print("var is 100")
print(var)
elif var == 150:
print("var is 150")
print(var)
elif var == 200:
print("var is 200")
print(var)
else:
print("None of the above.")
print(var)
x = 5
if x % 2 == 0 or x >= 0:
print('x is even or nonnegative')
else:
print('x is odd and negative')
range(stop): from 0 up to but not including stop
range(start, stop): from start up to but not including stop
range(start, stop, step): from start up to but not including stop with stepsize = step.
for i in range(6):
print(i)
for i in range(2, 5):
print(i, end=",") # separated by commas
for i in range(1, 9, 2):
print(i, end=" ") # separated by spaces.
count = 0
while count < 5:
print(count)
count += 1 # This is the same as count = count + 1
count = 0
while True:
print(count)
count += 1
if count >= 5:
break #break is used to exit a loop
break is used to exit a for loop or a while loop, whereas continue is used to skip the current block, and return to the "for" or "while" statement.
# Prints out only odd numbers - 1,3,5,7,9
for x in range(10):
if x % 2 == 0:
continue #continue is used to skip the current block,
#and return to the "for" or "while" statement.
print(x)
import math # use math.sqrt()
root1 =
root2 =
print(root1, root2)
# you can use single, double or triple quotes.
x = "I LOve Python!"
x = "I LOVE ProGRAMming "