Mark max value and min value with red circle

Hey I need to mark max and min value of this graph with a red circle.

f = importdata("croc.txt");
deviation = f.data(:,1);
dates = f.textdata;
x = datenum(dates, "yyyy/mm");
y = deviation;
figure(1);
plot(x,y)
datetick('x','yyyy')

How can I then mark min and max peak with red circle?

Answer 1

[dpb]

[~,imx]=max(y);
[~,imn]=min(y);
hold on
plot(x([imn;imx]),y([imn;imx]),'or')

or as I was going to do originally as noted in comment:

ix=[imn;imx];
plot(x(ix),y(ix),'or')

[Mathias Pettersen]

I get this error: Invalid expression. When calling a function or indexing a variable, use parentheses. Otherwise, check for mismatched delimiters.

[dpb]

Oh,yeah...I was going to make a new variable and then didn't..then didn't add the parens for indexing but just pasted. Adde () around the [] for the indexing expression. Fixed above...

[Mathias Pettersen]

I tried like this

plot(x(indexMin;indexMax),y(indexMin;indexMax),'or')

but didnt work

Also like this:

plot(x(indexMin,indexMax),y(indexMin,indexMax),'or')

but then got error: Index in position 2 exceeds array bounds (must not exceed 1).

[dpb]

Well, you did something wrong...the logic will work if x,y are vectors.

x=1:10;                    % make up some sample data
y=rand(size(x));
plot(x,y)                  % plot it
[~,imn]=min(y);            % get min/max locations
[~,imx]=max(y);
hold on                    % hold the plot to add to it
plot(x([imn;imx]),y([imn;imx]),'or')  % option one with given locations
ix=[imn;imx];                         % second option to build index
plot(x(ix),y(ix),'xk')                % plot that way different syhmbol

results in

that shows both markers at obviously the right locations.

[dpb]

plot(x(indexMin;indexMax),y(indexMin;indexMax),'or')

Indeed, you did do something wrong -- you wrote the subscripting expression as a 2D array expression, not as a vector of 1D indices.

NB: the difference in what wrote and the Answer or example.

[PAVARNA TA]

how to mark only the minimum or the maximum point?

[dpb]

Just leave out the one not wanted...