Part 2, Patterns, algorithms and programs 2

Question 1

This can be used to produce a sequence of numbers and store the sequence inside a list

Answer 1

when might you apply the list generation pattern

Question 2

in python how would you append an item to an end of a list

Answer 2

to perform this follow the following syntax

List = []

List = list + [1]

Question 3

1  initialise the input with a non-empty list

2  set best to the first item in the list

3  for each item in the list:

 3a   if the item is better than best:

  3ai    set best to the item

1.  print best

Answer 3

what are the 6 steps of the find the best value pattern

Question 4

what are the seven steps involved with the list transformation pattern

Answer 4

 initialise the input_list with the given values

2  initialise other inputs of the problem

3  initialise the output_list to the empty list

4  for each input_value of the input_list:

 4a   transform the input_value into an output_value

 4b   append the output_value to the output_list

1.  print the output_list

Question 5

1  initialise the input list

2  set found to the null value

3  for each item in the list:

 3a   if the item satisfies the condition:

  3ai    set found to the item

4  print found

Answer 5

what are the 6 steps of the find value pattern

Question 6

what do these two considerations refer to

1. the min and max size of the list itself
2. the min/max and boundary values of the elements inside the list

Answer 6

when testing lists what are two considerations that must be taken into consideration when writing tests

Question 7

what are these a sub category of

1. counting problems
2. aggregation problems
3. retrieval (or search) problems

Answer 7

name 3 types of reduction problems

Question 8

what are the 6 steps of the find value pattern

Answer 8

1  initialise the input list

2  set found to the null value

3  for each item in the list:

 3a   if the item satisfies the condition:

  3ai    set found to the item

4  print found

Question 9

how is the value NULL expressed in python

Answer 9

this is expressed as None in python

(note the capital N)

Question 10

when would you apply the find the best value pattern to an algorithm

Answer 10

This pattern can be used to find the best value in the list such as the hottest or coldest day

(note it has 1 redundant check being the first item in the list and returns the first best item found)

Question 11

what are the 7 steps involved with the list filtering pattern

Answer 11

1  initialise the input_list with the given values

2  initialise other inputs of the problem

3  initialise the output_list to the empty list

4  for each input_value of the input_list:

 4a   if the input_value satisfies the condition:

  4ai    append the input_value to the output_list

1.  print the output_list

Question 12

This pattern can be applied in problems that involve counting how many items are in a list or counting how many of the items in the list satisfy a given condition

Answer 12

explain when the counting problem can be applied to an algorithm

Question 13

to perform this follow the following syntax

List = []

List = list + [1]

Answer 13

in python how would you append an item to an end of a list

Question 14

when would we apply the list transformation pattern

Answer 14

This pattern can be used in cases where we wish to transform every element in a list into a new value

Question 15

in python how can you iterate over all values in a list while at the same time using the currently held value from the list from the iteration

Answer 15

when might you use this

For element in list:

If element > 30:

Do something

Question 16

what are the 6 steps of the aggregate pattern

Answer 16

1 initialise the input list

2  initialise the aggregator with a suitable value

3  for each number in the list:

 3a   if the number satisfies the condition:

  3ai    update the aggregator according to the value of the number

4  print the aggregator

Question 17

what does the following python function do

sum()

Answer 17

which python function does this describe

returns a number, the sum of all items in an iterable.

Question 18

when would you apply the aggregate pattern

Answer 18

This pattern may be applied when we need to aggregate (something formed by adding together several amounts or things) all numbers in a list or when we want to only aggregate the numbers in a list that satisfy a certain condition

Question 19

name 3 types of reduction problems

Answer 19

what are these a sub category of

1. counting problems
2. aggregation problems
3. retrieval (or search) problems

Question 20

explain when the counting problem can be applied to an algorithm

Answer 20

This pattern can be applied in problems that involve counting how many items are in a list or counting how many of the items in the list satisfy a given condition

Question 21

this term involves taking a list and producing a single value from the values in the original list

Answer 21

what does the term reduce/reduction mean in terms of lists

Question 22

which python function does this describe

returns a number, the sum of all items in an iterable.

Answer 22

what does the following python function do

sum()

Question 23

This pattern may be applied when we need to aggregate (something formed by adding together several amounts or things) all numbers in a list or when we want to only aggregate the numbers in a list that satisfy a certain condition

Answer 23

when would you apply the aggregate pattern

Question 24

Iterable: Required. The sequence to sum

Start: Optional. A value that is added to the return value

Answer 24

the syntax for the python sum() function is as follows but what are each of the parameters for

sum(iterable, start)

Question 25

when might you use this

len(object)

Answer 25

using python youd like to find the length of an object (list, string, etc) which built in function would you use

Question 26

1 initialise the input with a non-empty list

2  set best_position to 0

3  for each position from 1 to length of list – 1:

 3a   if the item at position is better than the item at best_position:

  3ai    set best_position to position

1.  print best_position

Answer 26

what are the 6 steps of the find position of first best value pattern

Question 27

when would you apply the find value pattern to an algorithm

Answer 27

This pattern can be applied when we wish to extract or search for a single value from a list (note the item returned will be the last item found that satisfied the condition)

Question 28

 initialise the input_list with the given values

2  initialise other inputs of the problem

3  initialise the output_list to the empty list

4  for each input_value of the input_list:

 4a   transform the input_value into an output_value

 4b   append the output_value to the output_list

1.  print the output_list

Answer 28

what are the seven steps involved with the list transformation pattern

Question 29

1 initialise the input list

2  initialise the aggregator with a suitable value

3  for each number in the list:

 3a   if the number satisfies the condition:

  3ai    update the aggregator according to the value of the number

4  print the aggregator

Answer 29

what are the 6 steps of the aggregate pattern

Question 30

the syntax for the python sum() function is as follows but what are each of the parameters for

sum(iterable, start)

Answer 30

Iterable: Required. The sequence to sum

Start: Optional. A value that is added to the return value

Question 31

This pattern can be used to find the best value in the list such as the hottest or coldest day

(note it has 1 redundant check being the first item in the list and returns the first best item found)

Answer 31

when would you apply the find the best value pattern to an algorithm

Question 32

what are the 6 steps of the find position of first best value pattern

Answer 32

1 initialise the input with a non-empty list

2  set best_position to 0

3  for each position from 1 to length of list – 1:

 3a   if the item at position is better than the item at best_position:

  3ai    set best_position to position

1.  print best_position

Question 33

this is expressed as None in python

(note the capital N)

Answer 33

how is the value NULL expressed in python

Question 34

1  initialise the inputs

2  set value to the first value of the sequence

3  set sequence to the empty list

4  append value to the sequence

5  while the termination condition is not true:

 5a   set value to the next value of the sequence

 5b   append value to the sequence

1.  print the sequence

Answer 34

what are the 8 steps involved with the list generation pattern

Question 35

1  initialise the input_list with the given values

2  initialise other inputs of the problem

3  initialise the output_list to the empty list

4  for each input_value of the input_list:

 4a   if the input_value satisfies the condition:

  4ai    append the input_value to the output_list

1.  print the output_list

Answer 35

what are the 7 steps involved with the list filtering pattern

Question 36

what are the 6 steps of the counting problem

Answer 36

1  initialise the input list

2  set a counter to zero

3  for each item in list:

 3a   if the item satisfies the condition:

  3ai    increment the counter, i.e. add 1 to it

4  print the counter

Question 37

using python youd like to find the length of an object (list, string, etc) which built in function would you use

Answer 37

when might you use this

len(object)

Question 38

This pattern can be used in cases where we wish to transform every element in a list into a new value

Answer 38

when would we apply the list transformation pattern

Question 39

when might you apply the list generation pattern

Answer 39

This can be used to produce a sequence of numbers and store the sequence inside a list

Question 40

This pattern can be applied when we wish to extract or search for a single value from a list (note the item returned will be the last item found that satisfied the condition)

Answer 40

when would you apply the find value pattern to an algorithm

Question 41

when might you apply the list filtering pattern

Answer 41

This can be used to filter out particular values from a given list

Question 42

when testing lists what are two considerations that must be taken into consideration when writing tests

Answer 42

what do these two considerations refer to

1. the min and max size of the list itself
2. the min/max and boundary values of the elements inside the list

Question 43

1  initialise the input list

2  set a counter to zero

3  for each item in list:

 3a   if the item satisfies the condition:

  3ai    increment the counter, i.e. add 1 to it

4  print the counter

Answer 43

what are the 6 steps of the counting problem

Question 44

This is similar to Pattern 2.8 find the best value however it has no redundant checks and instead returns the position/index of the best value

Answer 44

when would you apply the find position of first best value pattern to an algorithm

Question 45

This can be used to filter out particular values from a given list

Answer 45

when might you apply the list filtering pattern

Question 46

when might you use this

For element in list:

If element > 30:

Do something

Answer 46

in python how can you iterate over all values in a list while at the same time using the currently held value from the list from the iteration

Question 47

what are the 6 steps of the find the best value pattern

Answer 47

1  initialise the input with a non-empty list

2  set best to the first item in the list

3  for each item in the list:

 3a   if the item is better than best:

  3ai    set best to the item

1.  print best

Question 48

when would you apply the find position of first best value pattern to an algorithm

Answer 48

This is similar to Pattern 2.8 find the best value however it has no redundant checks and instead returns the position/index of the best value

Question 49

what does the term reduce/reduction mean in terms of lists

Answer 49

this term involves taking a list and producing a single value from the values in the original list

Question 50

what are the 8 steps involved with the list generation pattern

Answer 50

1  initialise the inputs

2  set value to the first value of the sequence

3  set sequence to the empty list

4  append value to the sequence

5  while the termination condition is not true:

 5a   set value to the next value of the sequence

 5b   append value to the sequence

1.  print the sequence