Using Randperm between two values

I'm creating a random lottery number generator that have to fill different requirements. The first requirement was as followed:

Generate and display a list of 7 numbers from the numbers 1 through 59.

To complete it I used this

n = randperm(59); numbers = n(1:7)

However the next requirement was to:

Generate and display a list of 8 numbers from the numbers 60 through 75.

I cannot find a way to use randperm between to values with one of them not being 1. I tried using randi, however it repeats numbers and one of the requirements is to not repeat any numbers.

Thanks for the assistance.

[Paul Munro]

59+randperm(1,16)

Answer 1

[Geoff Hayes]

Danté - if randperm(n) returns a row array containing a random permutation from integers from one to n inclusive, then couldn't you try something like

 randperm(16,8) + 59

where randperm(16,8) will return eight integers selected randomly from 1 through 16. We add 59 so that the integers now fall in the interval (60,75) which I think is what you want.

[Danté Davids]

Ah, it seems so simple now. This really helped me better my understanding of how Matlab works. Thank you.

Answer 2

[Star Strider]

Try this:

NextRequirement = 60 + randperm(15, 8)

Answer 3

[John BG]

Danté

this is John BG <mailto:[e-mail] [e-mail]>

Just use the output of randperm to index [60:75]

set_60_75=[60:1:75]
set_60_75(randperm(16,8))

no repetitions

set_60_75(randperm(16,8))
ans =
    65    75    66    74    70    71    62    63
>> set_60_75(randperm(16,8))
ans =
    75    73    72    70    68    60    63    65
>> set_60_75(randperm(16,8))
ans =
    68    69    60    72    71    74    64    61
>> set_60_75(randperm(16,8))
ans =
    64    73    61    62    65    75    71    70
>> set_60_75(randperm(16,8))
ans =
    65    74    73    75    68    64    70    62
>> set_60_75(randperm(16,8))
ans =
    70    75    69    68    60    72    66    62

[John BG]

ok, but lottery systems, by definition, cannot have many winners, can they?

[Walter Roberson]

Depends what you mean by "many"

There are some lotteries which guarantee that the top prize will be awarded, which they achieve by only selecting from combinations that were sold.

In such a lottery, if everyone were to purchase the same combination of numbers (assuming the lottery allowed complete choice) then everyone would share equally in the prize.

According to https://en.wikipedia.org/wiki/National_Lottery_(United_Kingdom), in one year that one of the UK lotteries was run, the top prize was shared by 133 winners.

Answer 4

[Steven Lord]

Hint: what's interesting about y and z?

x = 1:6
y = x + 1
z = y - 1

Answer 5

[sanjay sutar]

i have a set of numbers like a= [2,2.5,3,3.5,4,5] . I want to create a set of 100 numbers which is random using numbers of set (a) only. can i use randperm for it. please let me know any other option.

[Steven Lord]

Does a have at least 100 elements? If so and if you want to draw without replacement then yes, you could use randperm to generate indices you can use to extract 100 elements from a.

If it doesn't have at least 100 elements, or if you want to draw with replacement, use randi to generate the indices.

[Image Analyst]

Expanding on @Steven Lord's comment above:

allowableValues = rand(1, 100); % Has 100 values here, but could be any number you want.
randomIndexes = randperm(numel(allowableValues))
% Generate random values.  It will have however many elements as are in allowableValues.
randomValues = allowableValues(randomIndexes) 

% OR
allowableValues = [2, 2.5, 3, 3.5, 4, 5] % Has less than 100 values.
randomIndexes = randi([1, numel(allowableValues)], 1, 100) % 100 or however many you want to generate.
randomValues = allowableValues(randomIndexes) % Obviously some values will be repeated.

[sanjay sutar]

@steven lord. Thank you very much sir.2nd option worked exactly how I expected.