Agenda Announcements Review Practise midterm 1/14/2013 CompSci101 - - PowerPoint PPT Presentation

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Oct 21, 2022 351 likes •415 views

Agenda Announcements Review Practise midterm 1/14/2013 CompSci101 Peter Lorensen 1 List comprehension [ element for element in sequence if element ] [ [ ] x for loop if salary= [850.0, 1250.0, 900.0, 1400.0, 1100.0] lowPay =

SLIDE 1

Agenda

Announcements
Review
Practise midterm

1/14/2013 CompSci101 Peter Lorensen 1

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List comprehension [ [

1/14/2013 CompSci101 Peter Lorensen 2

]

[ element for element in sequence if element ]

for loop if x

salary= [850.0, 1250.0, 900.0, 1400.0, 1100.0] lowPay = [ pay for pay in salary if pay < 1000.00 ] >>[ 850.0, 900.0 ]

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Set

Set is similar to a list, but can only have unique

elements.

Set are unordered. No index.
Use set() or set(list) to create a set. Then add.

1/14/2013 CompSci101 Peter Lorensen 3

passengers = set([“John”, “Bob”, “Lisa”]) passengers.add(“peter”) >> set([“John”, “Bob”, “Lisa”, “peter”])

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Removing doublets from a list?

1/14/2013 CompSci101 Peter Lorensen 4

How do you remove doublets from a list?

custLst = list( set( custLst ) )

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Set

We often use for comparison

1/14/2013 CompSci101 Peter Lorensen 5

Operation Function Short Union set1.union( set2 ) | Intersection set1.intersection( set2 ) & Difference set1.difference( set2 )

Symmetric

difference set1.symmetric_differe nce( set2 ) ^

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APT MemberShip

1/14/2013 CompSci101 Peter Lorensen 6

def getThemOut():

baltimore = set([ "boar", "elephant", "zebra", "bear", "yellowFrog" ]) seattle = set(["snake", "stringRay", "yellowFrog"]) houston = set(["boar", "pig", "cow", "yellowFrog", "cat", "tiger"])

result = set() result = baltimore | seattle | houston result = baltimore & seattle & houston result = baltimore - seattle - houston return result