How to include this interpolation in a "for" loop?

Hi,

I would like to include this interpolation in a "for" loop. I have a number of sets of data and I would like to make a "for" loop for their interpolation. Can anyone please help me in making the loop?

    x1 = [1 4 8 10];
    y1 = [1 2 6 7];
    z1 = [2 3 5 9];

    x2 = [2 6 8 9]
    y2 = [5 9 7 6]
    z2 = [3 4 7 1]

    .
    .
    .
    xn = [       ]
    yn = [       ]
    zn = [       ]

w1 = interp1(x1,y1,5,'linear')
plot(x1,y1,'-',5,w,'*')

w2 = interp1(x2,y2,5,'linear')
plot(x2,y2,'-',5,w,'*')
.
.
.

wn = interp1(xn,yn,5,'linear')
plot(xn,yn,'-',5,w,'*')

Answer 1

[OCDER]

First, you have to rename all your variables. Labeling your variables x1,x2,x3 ...xn makes it very difficult to use a for loop. This is a fairly common problem that could be fixed using cell arrays. Read:

• https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval
• https://www.mathworks.com/help/matlab/cell-arrays.html

If you have 1000's of these variables... here's a solution that fixes that:

• https://www.mathworks.com/matlabcentral/answers/356673-operation-on-variables-whose-name-contain-a-certain-string

Best is to start by storing data in cells (use the find and replace option to fix x1 to x{1}, etc:

x{1} = 
y{1} = 
z{1} = 

x{2} = 
y{2} = 
z{2} = 

Then you can use for loops!

w = cell(size(x));
for k = 1:length(x)
   w{k} = interp1(x{k},y{k},5,'linear')
   plot(x{k},y{k},'-',5,w{k},'*')
   if k == 1  %In case you want to plot over many times
      hold on
   end
end

[Ismail Qeshta]

Thanks Donald

[Stephen23]

You could also use cellfun:

>> X = {[1,4,8,10],[2,6,8,9]};
>> Y = {[1,2,6, 7],[5,9,7,6]};
>> fun = @(x,y)interp1(x,y,5,'linear');
>> C = cellfun(fun,X,Y,'uni',0)

this makes it simple to put all of the output values into one array and then plot it.

[Ismail Qeshta]

Thanks Stephen