Week 2 - Escape sequences, Additional Basic Practice Problems

Liaw Bei Le · April 3, 2021

Learning Python Practices

Escape sequences
Extra mini tips for the basics
Additional Practices

What I learnt:

1. Escape sequences

Escape sequences allow us to include special characters in strings.

We can add a backslash \ before the character we want to escape.

‘ apostrophe within single quotes

sentence = 'Hey, that\'s my bag.'
print(sentence)

Output:

Hey, that's my bag.

’’ ‘‘ quotes within quotes

sentence = "They are the so-called \"cool kids\" in school."
print(sentence)

Output:

They are the so-called "cool kids" in school.

\n to create a new line and generate multi-line strings.

print("Hello this is\na random\nstring.")

Output:

Hello this is
a random
string.

\t tab

print("Hello this is\n\ta random\n\t\tstring.")

Output:

Hello this is
  a random
      string.

\ backslash character

print("C:\\Users\\Me\\Desktop")

Output:

C:\Users\Me\Desktop

Raw strings treats backslash \ as a literal character.
A raw string can be used by prefixing the string with r or R, allowing backslashes without needing to escape them.
But unescaped backslashes at the end of a raw string will cause an error.
```
print(r"Backslashes \ don't need to be escaped in raw strings.")
```
Output:
```
Backslashes \ don't need to be escaped in raw strings.
```

2. Extra mini tips for the basics

input( ) function always gives a string value by default
We can duplicate the same string multiple times, using *
```
string = 'Ann'
print(string*3)
```
Output:
```
AnnAnnAnn 
```
Combining variables/ values:
- comma , gives a space between values
- meanwhile, + is concatenate and doesn’t give a space between outputs
  - + will not work if using different data types e.g. string + integer
    string1='hello' print(string1,'Joe') print(string1+'Joe')
    Output:
    hello Joe helloJoe
- can use f strings to concatenate as well f”{ } { }”
```
firstname = "Joe"
lastname = "Tan"
print(f"{firstname} {lastname}")
```
  Output:
```
Joe Tan
```
use ” “ not “” for one spacing

Additional Practices

Sorting items into lists

foot_bones = ["calcaneus", "talus", "cuboid", "navicular", "lateral cuneiform", 
          "intermediate cuneiform", "medial cuneiform"]
longer_names = []
shorter_names = []
for bone_name in foot_bones:
  if len(bone_name) < 10:
      shorter_names.append(bone_name)
  else:
      longer_names.append(bone_name)
print(shorter_names)
print(longer_names)

Output:

['calcaneus', 'talus', 'cuboid', 'navicular']
['lateral cuneiform', 'intermediate cuneiform', 'medial cuneiform']

Sorting items in lists into strings

foot_bones = ["calcaneus", "talus", "cuboid", "navicular", "lateral cuneiform", 
          "intermediate cuneiform", "medial cuneiform"]
longer_names = ""
shorter_names = ""
for bone_name in foot_bones:
  if len(bone_name) < 10:
      shorter_names += "\n" + bone_name
  else:
      longer_names += "\n" + bone_name
print(shorter_names)
print(longer_names)

Output:

calcaneus
talus
cuboid
navicular
lateral cuneiform
intermediate cuneiform
medial cuneiform

Using \n and \t escape characters

print("Twinkle, twinkle, little star, \n\tHow I wonder what you are! \n\t\tUp above the world so high, \n\t\tLike a diamond in the sky. \nTwinkle, twinkle, little star, \n\tHow I wonder what you are!")

Output:

Twinkle, twinkle, little star, 
  How I wonder what you are! 
      Up above the world so high, 
      Like a diamond in the sky. 
Twinkle, twinkle, little star, 
  How I wonder what you are!

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