Outlines

• Jupyter Notebook
• Three ways to run python code
• Basic python data type and structure
• Basic python operators
• f-strings

Jupyter Notebook

• Open source web application
• Share documents that contain code, results, visualizations etc.
• Python version of R markdown
• In class demonstration will be performed in Jupyter Notebook
• HW will be released in Jupyter Notebook format

How to start Jupyter Notebook

Recommended approach in this class

• Install Anaconda https://www.anaconda.com
• Open Anaconda
• create an environment for the first time
• Select JupyterLab

How to Run Jupyter Notebook

• run code:
  • shift + enter
  • click run
• run markdown
  • select markdown instead of code
  • syntax is very similar to Rmarkdown
  • click the chunk, then press m
• file system
  • on the left hand side

Review Jupyter Notebook markdown (1)

• header

# Header 1
## Header 2
### Header 3
#### Header 4
##### Header 5
###### Header 6

• Markdown Next

Plain text  
End a line with two spaces to start a new paragraph.  
*italics* and _italics_  
**bold** and __bold__  
<span style="color:red">color</span>  
superscript^2^  
~~strikethrough~~  
[link](www.rstudio.com)   

Review Jupyter Notebook markdown (2)

• import an external image:

![](https://caleb-huo.github.io/teaching/2023FALL/logo.png){width=50%}

• inline equation, following latex format http://www.codecogs.com/latex/eqneditor.php

$A = \pi \times r^{2}$

• horizontal rule (or slide break):

***

Review Jupyter Notebook markdown (3)

• Unordered list

* unordered list
* item 2
    + sub-item 1
    + sub-item 2

• Ordered list

1. ordered list
2. item 2
    + sub-item 1
    + sub-item 2

Three ways to run python code

• python console

print("hello")

• Jupyter notebook

print("hello")

• run a standalone python script (e.g., hello.py) in terminal

python hello.py

4 basic data type

• integer

type(1)

## <class 'int'>

• floating point numbers

type(3.14)

## <class 'float'>

• strings

type("Hello")

## <class 'str'>

• boolean type

type(True)

## <class 'bool'>

type(False)

Conversion among 4 basic data types

int(1.1)

## 1

str(1.1)

## '1.1'

float("3.15")

## 3.15

int(True)

## 1

bool(0)

## False

str(False)

## 'False'

3 basci python data structure

• list
• tuple
• dictionary

list

names = ["Alice", "Beth", "Carl"]
len(names)

## 3

names[0]

## 'Alice'

names[-1]

## 'Carl'

• list is mutable

names[0] = "Alex"
names

## ['Alex', 'Beth', 'Carl']

Tuple

names = ("Alice", "Beth", "Carl")
names2 = "Alice", "Beth", "Carl"
len(names)

## 3

names[0]

## 'Alice'

names[-1]

## 'Carl'

• Tuple is not mutable

names[0] = "Alex"
names

list and tuple

• convert between list and tuple

a = [3,1]
tuple(a)

## (3, 1)

b = (3,1)
list(b)

## [3, 1]

sorted(a)

## [1, 3]

max(a)

## 3

min(b)

## 1

subsetting of list

• the element of a python list can be anything, even a list

data = [[1,2,3], [2,3,4]]
len(data)

## 2

data[1]

## [2, 3, 4]

data[1][1]

## 3

dictionary

• create a dictionary

phonebook = {"Alice": 2341, 
            "Beth": 4971,
            "Carl": 9401
}
phonebook

## {'Alice': 2341, 'Beth': 4971, 'Carl': 9401}

phonebook["Alice"]

## 2341

items = [("Name","Smith"), ("Age", 44)]
d = dict(items)
d

## {'Name': 'Smith', 'Age': 44}

d = dict(Name="Smith", Age=44)
d

## {'Name': 'Smith', 'Age': 44}

Basic python operators

2*4

## 8

2**4 ## raise to the power

## 16

7//4

## 1

"Hello" + "World"

## 'HelloWorld'

False and True

## False

False or True

## True

a = 10
a = a * 5
print(a)

## 50

a = 10
a *= 5
print(a)

## 50

Basic string operators

a = "greetings"
len(a)

## 9

a[0]

## 'g'

a[len(a) - 1]

## 's'

a[0:4]

## 'gree'

a[4]

## 't'

• The slicing (e.g., 0:4) is exclusive, it doesn’t include the last number n. 
• For example, a[0:4] will produce a[0], a[1], a[2], and a[3]

Basic string operators

a = "Hello"
a = a + "World"
print(a)

## HelloWorld

a = "Hello"
a += "World"
print(a)

## HelloWorld

Basic string operators

a = "greetings"
a[1:]

## 'reetings'

a[:3]

## 'gre'

a[:-1]

## 'greeting'

a[0:7:2] ## step size 2, default is 1 

## 'getn'

a[-1:0:-1]

## 'sgniteer'

a[::-1]

## 'sgniteerg'

b = "Hi"
b * 3

## 'HiHiHi'

name = "Lucas"
b + " " + "Lucas" + ", " + a

## 'Hi Lucas, greetings'

• new line: \n

res = b + " " + "Lucas" + "\n" + a
print(res)

## Hi Lucas
## greetings

python comments

• comments: ##

1+10 ## here is a comment

## 11

• Below is the syntax for a long string

"""
XXX
XXXX
"""

• This is also used for comments with more than 1 lines.
• print will convert “\n” to a new line

a = """
XXX
XXXX
"""

a

## '\nXXX\nXXXX\n'

print(a)

## 
## XXX
## XXXX

python string formatting

name = 'Alex'
age = 27

print('%s is %d years old' % (name, age))

## Alex is 27 years old

print('{} is {} years old'.format(name, age))

## Alex is 27 years old

print(f'{name} is {age} years old') 

## Alex is 27 years old

We will focus on the f-string in this class

f'{}'

Python f-string expressions

• We can put expressions between the {} brackets.

bags = 4
apples_in_bag = 10

print(f'There are total of {bags * apples_in_bag} apples')

## There are total of 40 apples

print(f'There are {bags} bags, and {apples_in_bag} apples in each bag.\nSo there are a total of {bags * apples_in_bag} apples')

## There are 4 bags, and 10 apples in each bag.
## So there are a total of 40 apples

f-string formatting float (precision)

• precision
  • The precision is a value that goes right after the dot character.

val = 12.3

print(f'{val:.2f}')

## 12.30

print(f'{val:.5f}')

## 12.30000

f-string formatting float (width)

• width
  • The width specifier sets the width of the value.
  • The value may be filled with spaces if the value is shorter than the specified width.

val = 12.3

print(f'{val:2}')

## 12.3

print(f'{val:7}')

##    12.3

print(f'{val:07}')

## 00012.3

for x in range(1, 11):
    print(f'{x:02} {x*x:3} {x*x*x:4}')

f-string formatting float

• precision + width

f'{value:{width}.{precision}}'

f'{5.5:10.3f}'

## '     5.500'

from math import pi ## will introduce more about python module in the fuction lecture
pi

## 3.141592653589793

f'{pi:10.6f}'

## '  3.141593'

• comma separater for larger number

f'{pi*100000:,.2f}'

Input function

• Input function
  • Allows input from users.

username = input("What is your name?")
print("Hello " + username)

• f string

print(f"Hello {username}")

• Another example:

num1 = input("First number:")
num2 = input("Second number:")
res = int(num1) + int(num2)
print(res)
print(f"{num1} plus {num2} is {res}")

Reference

• https://docs.python.org/3/index.html
• https://github.com/Apress/beginning-python-3ed