S13-Words-for-the-Future-notebooks/python-cheatsheet.ipynb

Python cheatsheet¶

(non-complete, please use, modify, (re)publish!)

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string, integer, float¶

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x = '3'
y = 3
z = 3.5

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type(x)

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type(y)

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type(z)

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print(x * y) # Works

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print(x + y) # Does not work: TypeError

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# From int to str
str(y)

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# From str to int
int(x)

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# From float to int
int(z)

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string operations¶

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s = 'hello!'

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s.upper()

Out[12]:

'HELLO!'

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s.lower()

Out[13]:

'hello!'

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s.capitalize()

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s.title()

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s.replace('e', 'a')

Out[15]:

'hallo!'

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s.strip('!')

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s.count('l')

Out[14]:

2

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s.endswith('o')

Out[16]:

False

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s.startswith('h')

Out[17]:

True

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# format a string
name = 'you'
t = 'hello {}'.format(name)
print(t)

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# format a string (different way of writing the same!)
name = 'you'
t = f'hello {name}'
print(t)

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loops¶

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if/elif/else¶

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# check if a word is in a list
words = ['hello', 'language', 'weaving']
word = 'quilting'
if word in words:
    print(f'{word} is in the list!')
else:
    print(f'{word} is NOT in the list!')

quilting is NOT in the list!

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# check if a letter is in a word
words = ['hello', 'language', 'weaving']
letter = 'a'
for word in words:
    if letter in word:
        print(f'the letter "{letter}" is in the word "{word}"!')
    else:
        print(f'the letter "{letter}" is NOT in the word "{word}"!')

the letter "a" is NOT in the word "hello"!
the letter "a" is in the word "language"!
the letter "a" is in the word "weaving"!

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# check if a word is in a sentence
sentences = [
    'Software and language are intrinsically related, since software may process language, and is constructed in language.', 
    'Yet language means different things in the context of computing: formal languages in which algorithms are expressed and software is implemented, and in so-called “natural” spoken languages.', 
    'There are at least two layers of formal language in software: programming language in which the software is written, and the language implemented within the software as its symbolic controls.'
]
word = 'programming'
for sentence in sentences:
    print('---')
    if word in sentence:
        print(f'YES, the word "{word}" is in the sentence "{sentence}"!')
    else:
        print(f'NO, the word "{word}" is NOT in the sentence "{sentence}"!')

---
NO, the word "programming" is NOT in the sentence "Software and language are intrinsically related, since software may process language, and is constructed in language."!
---
NO, the word "programming" is NOT in the sentence "Yet language means different things in the context of computing: formal languages in which algorithms are expressed and software is implemented, and in so-called “natural” spoken languages."!
---
YES, the word "programming" is in the sentence "There are at least two layers of formal language in software: programming language in which the software is written, and the language implemented within the software as its symbolic controls."!

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# check if a word ends with "ing"
words = ['hello', 'language', 'weaving']
for word in words:
    if word.endswith('ing'):
        print(f'YES, the word "{word}" ends with "-ing"!')
    else:
        print(f'NO, the word "{word}" DOES NOT end with "-ing"!')

NO, the word "hello" DOES NOT end with "-ing"!
NO, the word "language" DOES NOT end with "-ing"!
YES, the word "weaving" ends with "-ing"!

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lists¶

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# Make an empty list
bag = []

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type(bag)

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# Add items to the list
word = 'hello'
bag.append(word)
print(bag)

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# From list to string
' --- '.join(bag)

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dictionaries¶

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# Make an empty dictionary
d = {}

# or

d = dict()

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d['word'] = 10  
print(d)

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d.keys()

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open(), read(), write(), close()¶

mode can be:

• r when the file will only be read
• w for only writing (an existing file with the same name will be erased)
• a opens the file for appending, any data written to the file is automatically added to the end
• r+ opens the file for both reading and writing

(The mode argument is optional: r will be assumed if it’s omitted.)

https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files

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# open(), read()
txt = open('txt/language.txt', 'r').read()
print(txt)

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# readlines()
lines = open('txt/language.txt', 'r').readlines()
print(lines)

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# listdir() (open multiple files in a folder)
import os
folder = 'txt/words-for-the-future/'
for file in os.listdir(folder):
    print(folder+file)
    # txt = open(folder+file).read()
    # print(txt)

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# write() (returns a number, this is how many characters have been written to the file)
out = open('out.txt', 'w')
out.write('Hello!')

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