4.2: Functions

Last updated
Save as PDF

Page ID: 357704

\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

Predefined Functions

General Purpose Functions - functions like print

Type Conversion

Functions convert variables between data types

int()
float()
bool()
str()

Methods

String methods

molecule ="Aspirin is an anti-inflammatory"
print(molecule.capitalize())
print(molecule.replace("in","ins"))
print(molecule.index("r"))
print(molecule.lower())
print(molecule.find('i'))
print(molecule.find('is'))
print('is an' in molecule)

Note, objects are immutable (when you print as capital, it is still lower case. In the last example we used the "in" operator and it returned a Boolean value (true)

List Methods

consider the list "molecules" that has aspirin (aspirin is the element of the list you want the index for)

molecule =["aspirin","caffeine","aspirin"]
print(molecule)
print(type(molecule))
print(molecule.index("aspirin"))
print(molecule.count("aspirin"))
molecule.append("acetic acid")
print(molecule)

Arithmetic Operators

binary operators in the sense that one thing is operating on another.

Operator Precedence is as in normal math

PEDMAS (parenthesis, exponents, multiplication, division, addition, subtraction)
BODMAS: B-Brackets, O-Orders (powers/indices or roots), D-Division, M-Multiplication, A-Addition, S-Subtraction.

print(4+3)
print(4*3)
print(4/3)
print(4//4)
print(4%3)
print(4**3)

7
12
1.3333333333333333
1
1
64

Augmented operators

These are unary operators in the sense that they operate on one thing

x=4
x=x+3
print(x)
x += 3
print(x)
x-=4
print(x)
x/=4
print(x)

Comparison operators (Boolean Expressions)

x=3>2
print(x)
x=3<2
print(x)
x=3<=2
print(x)
x=3>2
print(x)
x=3 == 2
print(x)
x=3 != 2
print(x)

True
False
False
True
False
True

Logical Operators

Bolean AND, OR and NOT

molar_mass = 124
print(molar_mass>100 and molar_mass <150)
molar_mass = 124
print(molar_mass<100 and molar_mass >150)
molar_mass = 160
print(molar_mass<100 and molar_mass >150)
molar_mass = 160
print(molar_mass<100 or molar_mass >150)
molar_mass = 124
print(not molar_mass<100)

True
False
False
True
True

Other operators

in (membership operator)

aspirin = 'C9H8O4'

print('H' in aspirin)
print('h' in aspirin)
print('He' in aspirin)
print('N' in aspirin)
print(40*"*")

aspirin_synonyms = [ "aspirin", "Dispril", "Ecotrin", "Polpirin", "Acetylsalicylic Acid"]

print( "Acetylsalicylic Acid" in aspirin_synonyms)
print( "Acid" in aspirin_synonyms)
print( "salicylic Acid" in aspirin_synonyms)
print( "Bufferin" in aspirin_synonyms)

Hello world!

Compound Statements

humidity = 50
if humidity >= 70:
 print("It is a himid day")
elif humidity > 40:
  print("It is a nice day")
else: 
  print("It is an arid")

It is a nice day