Hello, I'm struggling in a specific action in a pie graph. After I input a vector of numbers, if the sum of the numbers is bigger than 100, than the program should do the following action in a for loop.

afterwards a pie graph should be created and the numbers should be presented in their decimal value. my code works fine and creates the graph besides the decimal part. I would love to get a hand in here how to turn my values into their decimal values (I know this code won't do it, I'm not familiar with any command that would do that).

else sum(num) > 100

for i = 1 ; length(num) %for loop that takes every value, divides it by the sum of the vector and multiply by 100%

num(i) = ((num(i)/sum(num))*100);

end

pie(num);

thanks in advance.

Answer by dpb
on 3 May 2019

Edited by dpb
on 3 May 2019

Accepted Answer

...

for i = 1 ; length(num) % ";" should be ":"

num(i) = ((num(i)/sum(num))*100);

end

Use Matlab array syntax instead of loops...

num=100*num/sum(num); % Matlab is "MATrix LABoratory", use vectorized operations

pie(num,cellstr(num2str(num(:),'%05.2f%'))) % write percentages as labels

NB: the (:) on the num array to ensure is column vector in argument to num2str to ensure generates a columnar list of char strings; a row vector gets turned into one long string instead, not at all what you want.

"Salt to suit" the precision for the format string...

ADDENDUM/ERRATUM

Fixed missing cellstr() cast and mistyped format string (had 5f.2 rather than 5.2f)

Nitai
on 3 May 2019

hey DB, thx for your help. when i try to write this:

num=100*num/sum(num); % Matlab is "MATrix LABoratory", use vectorized operations

pie(num,num2str(num(:),'%05f.2')) % write percentages as labels

it won't work and displays the following error:

Error using pie (line 71)

X and EXPLODE must be the same length.

and i didnt completly understand your note at the end of your msg.

any thougths?

dpb
on 3 May 2019

Was off the doc; hadn't tried it...needs a cellstr() array, not a cell array of char() it appears...

pie(num,num2str(num(:),'%05.2f%')) % write percentages as labels

Actually, I see that if you're happy with just percentages as the integer values that pie does that automatically; you don't need to write the text at all...if you want more precision, looks like need to supply.

pie(num) % shows percentages as integers by default

As far as the last comment, see difference between

>> x % some sample percentage values

x =

33.33

35.29

3.92

15.69

11.76

>> cellstr(num2str(x,'%05.2f')) % x is column vector, get column of cellstr()

ans =

5×1 cell array

{'33.33'}

{'35.29'}

{'03.92'}

{'15.69'}

{'11.76'}

>> cellstr(num2str(x.','%05.2f')) % if x is row vector (.' does that to column)

ans =

1×1 cell array

{'33.3335.2903.9215.6911.76'}

>>

the last ends up with one long string of the numbers in internal storage order of the string representation of the values of x -- not at all what you want/need...

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