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value/object is interchangeable, assigned to variable |
type of value/object: print(type( )) |
type provides class: int, str, math, float, character |
integers with commas are not legal (ie 42,000 --> 42 0) |
integers with commas are treated as pair values |
Functions and Parameters
Function Definition Syntax |
def name( parameters ): statements |
The syntax for a function definition is:
Functions and Parameters
Function Style
def header():
indent 4 spaces for statements
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Compound Statements
used for conditional execution:
if_stmt ::= "if" expression ":" suite
( "elif" expression ":" suite )*
["else" ":" suite]
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Bugs
error: variables must already have values in order to be used on the rh side |
common errors: parse error (55%) type (15%) name (11%) value(10%) |
other errors: URI, Token, Syntax, TimeLimit, Indentation, Attribute, Import, Index |
ex's: parse: missing bracket, interprets as another parameter to function |
EOF..: python got to the end of the file and was still looking for something |
ValueError: when you pass a parameter to a function and the function - the type you pass is not the expected one |
Finding clues: print values and types in statement causing error |
Name Error: you already used that name, wrong name or input etc |
Bugs
1. Adding two strings is not the same as adding two integers (be aware to convert user inputs)
2. Test boundary conditions: inside, outside and parameters themselves .
3. Deal with input values outside the parameter: use modulo operator
Example: use %24 to keep within parameters (0,23)!
current_time= int(input("input hrs between 0-23")
wait_time= int(input("how many hours do you want to wait?")
final = (current_time + wait_time) % 24
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Creating an Algorithm
1. Design the algorithm (instructions with #)
2. Input code under hashes |
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Modules
modules are data objects - module objects contain other python elements |
1. import module as whatever |
to use something within a module, use dot notation |
turtle.Turtle : In the module turtle, access the Python element called Turtle |
others: math, random, pi, e |
example: math.sqrt(x), math.sin(math.radians(degrees)), math.pi will print 3.14.., math.e will print 2.718 |
random.random() gives random number between [0.0, 1.0) |
random.randrange(x,y) |
other modules to check out: game |
Examples
import random
howmany = 10
for counter in range(howmany):
arandom = random.random()
print(arandom) #prints 10 random numbers
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Important Section
Built In Types: Truth Values, Boolean Operators, Comparisons, (Bitwise operators), Additional methods on: integers, floats, strings, (Iterator and Generator Types), Sequence (str, list, tuple etc) Types, String Methods, String formatting, etc : https://docs.python.org/2/library/stdtypes.html
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