This workshop is licensed under a Creative Commons Attribution 4.0 International License.
General programming language...good at most tasks
CTRL + Enter will run a cell; Shift + Enter will run a cell and highlight the next cell.
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5 - 2
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= symbol assigns the value on the right to the name on the left.age
and a name in quotes to a variable first_name.
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age = 42
first_name = 'Ahmed'
_ (typically used to separate words in long variable names)__alistairs_real_age have a special meaning
so we won't do that until we understand the convention.print to display values.print that prints things as text.
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print(first_name, 'is', age, 'years old')
print automatically puts a single space between items to separate them.
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print(last_name)
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age = age + 3
print('Age in three years:', age)
int): represents positive or negative whole numbers like 3 or -512.float): represents real numbers like 3.14159 or -2.5.str): text.type to find the type of a value.type to find out what type a value has.
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print(type(52))
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height = 'average'
print(type(height))
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print(5 - 3)
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print('hello' - 'h')
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full_name = 'Ahmed' + ' ' + 'Walsh'
print(full_name)
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separator = '=' * 10
print(separator)
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print(len(full_name))
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print(len(52))
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print(1 + '2')
1 + '2' be 3 or '12'?
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print(1 + int('2'))
print(str(1) + '2')
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print('half is', 1 / 2.0)
print('three squared is', 3.0 ** 2)
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first = 1
second = 5 * first
first = 2
print('first is', first, 'and second is', second)
first when doing the multiplication,
creates a new value, and assigns it to second.second does not remember where it came from.
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# This sentence isn't executed by Python.
adjustment = 0.5 # Neither is this - anything after '#' is ignored.
print(adjustment)
len takes exactly one.int, str, and float create a new value from an existing one.print takes zero or more.print with no arguments prints a blank line.
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print('before')
print()
print('after')
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print(max(1,2,3))
print(min('a', 'A', '0'))
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print(max(1, 'a'))
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round(3.712)
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round(3.712, 1)
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help(round)
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text = 'Hello there, nice to meet you!'
print(text)
print(text.startswith('hell'))
print(text.replace('Hello','Goodbye'))
print(text.title().replace('!','?'))
import to load a library module into a program's memory.module_name.thing_name.. to mean "part of".datetime, one of the modules in the standard library:
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import datetime
today = datetime.datetime.now()
nextYear = today + datetime.timedelta(days=365)
print(today)
print(nextYear)
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help(datetime)
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from datetime import datetime, timedelta
today = datetime.now()
nextYear = today + timedelta(days=365)
print(today)
print(nextYear)
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import datetime as dt
today = dt.datetime.now()
nextYear = today + dt.timedelta(days=365)
print(today)
print(nextYear)
matplotlib plotting library is often aliased as plt.name_001, name_002, etc.,
would be at least as slow as doing them by hand.[...].,.len to find out how many values are in a list.
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names = ['Cathy','Doug','Monica','Jake','Peter']
print(type(names))
print('names:', names)
print('length:', len(names))
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print('zeroth item of names:', names[0])
print('fourth item of names:', names[4])
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names[0] = 'Catherine'
print('names is now:', names)
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primes = [2, 3, 5]
print('primes is initially:', primes)
primes.append(7)
primes.append(9)
print('primes has become:', primes)
append is a method of lists.object_name.method_name to call methods.help(list) for a preview.extend is similar to append, but it allows you to combine two lists. For example:
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teen_primes = [11, 13, 17, 19]
middle_aged_primes = [37, 41, 43, 47]
print('primes is currently:', primes)
primes.extend(teen_primes)
print('primes has now become:', primes)
primes.append(middle_aged_primes)
print('primes has finally become:', primes)
Note that while extend maintains the "flat" structure of the list, appending a list to a list makes the result two-dimensional.
del to remove items from a list entirely.del list_name[index] removes an item from a list and shortens the list.
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print('primes before removing last item:', primes)
del primes[4]
print('primes after removing last item:', primes)
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goals = []
goals.extend([1, 'Create lists.', 2, 'Extract items from lists.', 3, 'Modify lists.'])
print(goals)
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values = [1,3,4,7,9,13]
print(values[0:2])
print(values[:2])
print(values[2:])
print(values[:-1])
IndexError if we attempt to access a value that doesn't exist.
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print('99th element of element is:', element[99])
{...}."key":"value".,.
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students = {"firstName":"John","lastName":"Smith"}
print(type(students))
print(students)
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students["age"] = 19
print(students)
students["major"] = ["Art History","French"]
print(students)
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print(students["firstName"])
print(students['age'])
print(students['major'][1])
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courses = {"courses":[
{
"Title":"Intro to Economics",
"Instructor": {
"firstName": "Robert",
"lastName":"Schiller",
},
"Number": "ECON 101",
"Size": 65,
"isFull": True,
},
{
"Title":"Intro to French",
"Instructor": {
"firstName": "Marie",
"lastName": "Gribouille",
},
"Number":"FREN 101",
"Size": 15,
"isFull": False,
}
]}
print(courses)
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print(courses.keys())
print(courses.values())
'courses' is the top level or root elementcourses['courses'] is a list; it's items are accessed using the index.keys() & .values() lists the dictionary keys and values respectively at the current dictionary level
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print(courses['courses'][0].keys())
print(courses['courses'][0].values())
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print(courses['courses'][1]['Instructor']['lastName'])