Class 40 — December 4

Taking care of business

Take care of our world — For others need to follow — The path that you make

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Look both ways

• Back and ahead

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Please help out CS 1112

• Survey

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Agenda

• Chrestomathical and chrestohistorical

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Gallery

• Fall 2019 art exposition

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Downloads

• The below code fragments can be found in scraps.py

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Important patterns

• Print output

print( "ABCDE" )

x = 11

y = 12

z = x + y

print( x, "+", y, "+", z )

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• Get input

reply = input( "Enter data to be manipulated: " )

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• Convert input to data

reply = input( "Enter word: " )

w = reply.strip()

reply = input( "Enter integer: " )

n = int( reply )

reply = input( "Enter decimal: " )

n = float( reply )

reply = input( "Enter text: " )

words = reply.split()

reply = input( "Enter three integers: " )

sa, sb, sc = reply.split()

a, b, c = int( sa ), int( sb ), int( sc )

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• Perform calculations

import math

reply = input( "Enter radius: " )

r = int( reply )

circumference = 2 * math.pi * r

area = math.pi * ( r ** 2 )

reply = input( "Enter integer: " )

n = int( reply )

d1 = n % 10

d2 = n // 10 % 10

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• Process strings

reply = input( "Enter text: " )

s = reply.strip()

reply = input( "Enter key: " )

key = reply.strip()

no_caps_version = s.lower()

nbr_occurrences = s.count( key )

first_occurrence = s.find( key )

second_occurrence = s.find( key, first_occurrence + 1 )

slice = s[ first_occurrence : second_occurrence ]

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• Get web input

import url

hangman_url = "http://www.cs.virginia.edu/~cs1112/words/hangman"

tough_words = url.get_contents( hangman_url )

• Examine and create lists

• Convert a string into a list of strings

reply = input( "Enter text: " )

words = reply.split()

• Convert a list of strings into a list of numbers

reply = input( "Enter integers: " )

numeric_strings = reply.split()

integers = []

for s in numeric_strings :

  i = int( s )

  integers.append( i )

• Perform an accumulation

sum = 0

product = 1

for i in integers :

  sum = sum + i

  product = product * i

series = []

for i in range( 0, n ) :

  value = 2 ** i

  series.append( value )

canonical_strings = []

for s in strings :

  s = s.strip().lower()

  canonical_strings.append( s )

• Check to see if the elements of the list are all of the same form

are_all_positive = True

for i in integers :

  if ( i < 0 ) :

  are_all_positive = False

  break

• Check to see if any element of the list has a desired form.

some_are_positive = False

for i in integers :

  if ( i >= 0 ) :

  some_are_positive = True

  break

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• Generate random data

• Get a random value from a range

import random

i = random.randrange( 0, 100 )

• Select a random element from a list

import random

s = random.choice( strings )

• Produce a random sentence (gibberish)

import random

sentence = ""

for i in range( 0, 5 ) :

  word = random.choice( words )

  sentence = sentence + word + " "

sentence = sentence.strip()

• Produce a random tuple

import random

r = random.randrange( 0, 255 )

g = random.randrange( 0, 255 )

b = random.randrange( 0, 255 )

pixel = ( r, g, b )

• Index of first matching element

if key in integers :

  i = integers.index( key )

else :

  i = -1

• Compare two lists

pairwise_sorted = True

n = len( list1 )

for i in range( 0, n ) :

  w1 = list1[ i ]

  w2 = list2[ i ]

  if ( w1 > w2 ) :

  pairwise_sorted = False

  break

• Synthesize two lists

n = len( list1 )

merged_list = []

for i in range( 0, n ) :

  w1 = list1[ i ]

  w2 = list2[ i ]

  merged_list.append( w1 )

  merged_list.append( w2 )

 

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© 2019 Jim Cohoon

Resources from previous semesters are available.