Plotting the probability of drawing a Spade

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Cole  Kleinow
Cole Kleinow on 14 Feb 2021
Answered: Image Analyst on 4 Jun 2022 at 14:30
so i need to plot the probability of drawing a spade out of 100 draws (card replaced each time) but i cant quite figure out what to math against what
Deck = [];
Hearts = 0;
Spades = 0;
Diamonds = 0;
Clubs = 0;
n = 100;
Drawn = [];
for rank = 1:13
for suit = 1:4
cardval = [rank suit];
Deck = [Deck, {cardval}];
end
end
for tries = 1:n
Shuffled = Deck(randperm(length(Deck)));
Card = Shuffled(1,1);
Drawn = [Drawn,Card];
if Card{1}(2) == 1
Hearts = Hearts + 1;
elseif Card{1}(2) == 2
Spades = Spades + 1;
elseif Card{1}(2) == 3
Diamonds = Diamonds + 1;
else
Clubs = Clubs + 1;
end
end
SuitsDrawn = [Hearts Spades Diamonds Clubs];
edges = min(Spades):max(Spades);
counts = histc(Spades, edges);
grandTotalSum = sum(counts(:));
normalizedCountSums = counts / grandTotalSum;
plot(edges, normalizedCountSums)
  1 Comment
Cris LaPierre
Cris LaPierre on 15 Feb 2021
How many cards are in a deck? How many of those cards are spades?

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Answers (2)

Vimal Rathod
Vimal Rathod on 19 Feb 2021
Hi,
Probability of drawing spades from 100 draws is still one single value. You can try adding a for loop over the for loop with tries. This way you will get many values of probability of drawing spades from 100 draws. Then you could plot all those points by saving the edges and normalizedCountSums as arrays.
% getting 10 different probability values for
% probability of drawing spades from 100 draws
for set = 1:10
for tries = 1:n
% your code
end
% finding edges and NormalizedCountSums
%concatenate the edges and normalizedCountSums
..
..
end
Hope this helps!

Image Analyst
Image Analyst on 4 Jun 2022 at 14:30
Note that probability is not the count. There will be randomness unless you draw an infinite amount of times.
You can just identify each card with a number, then see how many times that number is drawn.
% Make 100 draws of 1 card each time.
numDraws = 100;
draws = randi([1, 52], numDraws, 1)
% Count each suit.
% Spades are identified as cards 1-13.
% Clubs are identified as cards 14-26.
% Hearts are identified as cards 27-39.
% Diamonds are identified as cards 40-52.
spadeCount = sum(draws >= 1 & draws <= 13)
clubCount = sum(draws >= 14 & draws <= 26)
heartCount = sum(draws >= 27 & draws <= 39)
diamondCount = sum(draws >= 40 & draws <= 52)
% Compute percentages, which is only an approximation of probability.
spadePercentage = 100 * spadeCount / numDraws
clubPercentage = 100 * clubCount / numDraws
heartPercentage = 100 * heartCount / numDraws
diamondPercentage = 100 * diamondCount / numDraws

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