Python has five standard data types −
- Numbers
- String
- List
- Tuple
- Dictionary
You can only print strings.
You can convert other variable types to string by using str() function
enumerate() instead of using index.
Example:
List
list = [ 'abcd', 786 , 2.23, 'john', 70.2 ]
Tuples
Tuples are like lists but us round brackets and can be though of as read only lists.
tuple = ( 'abcd', 786 , 2.23, 'john', 70.2 )
Dictionary
Dictionary is an associative array
tinydict = {'name': 'john','code':6734, 'dept': 'sales'}
To retrieve the data from the dictionary, you can use either of these two approaches:
tinydict['name']
tinydict.get('name', 'Not Found') # this method is cleaner at handling error conditions. It returns Not found if the 'name' doesn't exist
Screen Output Methods
Assignment 1 Question 3
4 different print methods. Plain print() and then with each of the following:
print()
- .title
- .upper
- .lower
Assignment 2
Function Definitions: def function_name(passed_parameter)
function return
int() like str()
len()
.split() - to separate text by a definied separator
for loops
for Something in <name of list> cause the software to iterate through each item in the list
enumerate() provides converts a list to a numerically indexed array
.append() - add contents of append to the end of the list
reversed() - allows you to iterate through a list in reverse order when using a for loop
slices of lists - alows you to get specific parts of a list listname[start_index: end_index] - listname[:3] gives you the list up to but not including element number 3. listname[3:] gives you everything from 3 to the end.
https://towardsdatascience.com/python-basics-6-lists-and-list-manipulation-a56be62b1f95
Question 2
.remove(value) to remove item that has value of 'value' from a list
del(listname[x]) removes the item at index x from the list
Question 3
list comprehension https://docs.python.org/3/tutorial/datastructures.html#list-comprehensions
List Comprehensions Video: https://www.youtube.com/watch?v=AhSvKGTh28Q
List comprehensions are a more efficient way of populating lists that effectively allow you to combine some action with one or more for loops.
A list comprehension consists of brackets containing an expression followed by a for clause, then zero or more for or if clauses. The result will be a new list resulting from evaluating the expression in the context of the for and if clauses which follow it. For example, this listcomp combines the elements of two lists if they are not equal:
Example:
squares = [x**2 for x in range(10)]
Substrings is done in the same way slices act on lists. [x:y]
Error in Assignment: Question 1: "The reverse alphabetical order of the list is ['c', 'b', 'a', 'abc3', '3']" should be ['3', 'abc3', 'c', 'b', 'a']
Error in Assignment: Question 3: Should say using comprehensions, not say (not using a for loop).
Assignment 4
x = randint(1, 100) any random number between 1 and 100
Error in Assignment: Clarity: "Print out the two outcomes as well as the Sum" should say "Print the outcome of the two dice rolls as well as ..."
Demo Ligth Dependent Resistor
Error in Assignment: The assignment doesn't describe how to wire it properly.
Connect the positive power (+5V Pin 2) pin to one side of the CdS cell.
Connect the GPIO 4 (pin 7) to between the capacitor and the CdS cell.
Connect the other end of the capacitor to the ground (pin 6)
Other Pything stuff.
len()
\n for line return
e = sentence.find("a", 3, 20)
print(e)
.startswith() - returns true if the provided string starts with a string segment.
.count()
numbers.isnumeric()
format()
if / elif is the replacement for case statements in PHP
pull_up_down=GPIO.PUD_DOWN this is used in a GPIO.setup statement to set the begining state of a pin. If this isn't set, the pin could show an input or output voltage that is unpredicted. It might be on when you expect it to be off and off when you expect it to be on. Since you're likely using this input as a signal for something else, you want to know the state of it from the begining.