I would like to check that I have
workingDir = C:\Users\~\Temp\workspace_folder;
for i=1:2
% do an action which generates folder C:\Users\~\Temp\workspace_folder_1 first iteration
% and increment for each iteration
x = strcat(workingDir,'_',i);
end
it gives only
x = C:\Users\~\Temp\workspace_folder_ , why do it doesn't print me the iteration value?
I expected to have
C:\Users\~\Temp\workspace_folder_1
C:\Users\~\Temp\workspace_folder_2
Thanks
you need to convert i to string using int2str
Related
I'm trying to use writetable command inside a loop. Any help?
MonthNames=['JAN'; 'FEB'; 'MAR'; 'APR'; 'MAY'; 'JUN'; 'JUL'; 'AUG'; 'SEP'; 'OCT'; 'NOV'; 'DEC'];
for sensorIndex = 1:numel(sensor)
for monthIndex = 1:numel(MonthNames)
% Get the current sensor
k = sensor(sensorIndex);
% Get the file(s?) associated with that sensor
S = dir(fullfile(path, '*', sprintf('sensor%d.xls', k));
% Create an output filename
filename = sprintf('sensor%d_%s.xls', k, MonthNames(monthIndex));
% do your stuff
F = fullfile(S(k).folder,S(k).name);
data = readtable(F);
writetable(data, filename);
end
end
Doing it this way lets you optionally not have ALL months. Lots of ways to code it, but my personal preference is to keep loop variables as indices and grab the current variable inside the loop using that index.
I am trying to write a function transform(A) which when given a matrix A returns a new matrix. The new matrix should be obtained according to following:
if A has more than one row then interchange the first and second row. After this square the elements in the first row.
So far thats what I have written:
function[Anew] = transform(A)
dimension = size(A);
if dimension(1) > 1 %if there is more than 1 row
A([1 2],:)=A([2 1],:);
end
A(1,:,:) = A(1,:,:).^2 %squares elements in the first row
end
I tested my function by invoking it in matlab.
I noticed that because i dont have a semi colon next to A(1,:,:) = A(1,:,:).^2
I still obtain the desired result but not as output of the function.
I obtain A =
instead of Anew =
If i put a semi colon next to A(1,:,:) = A(1,:,:).^2; then I dont get an output at all.
Could you tell me what is wrong and what should I change in my program to obtain output as Anew?
Thank you
To return a value from a function in Matlab, you must directly assign to it.
In your case, you need to assign to Anew at the end of the operation (you could also technically just use that variable all-together).
function [Output1, Output2] = SomeFunction( ... )
% Do Some Work
% Store Output
Output1 = Result1(:,2) %some output
Output2 = Result2(3:end, :) %some other result
end
function[Anew] = transform(A)
dimension = size(A);
Anew = A;
if dimension(1) > 1 %if there is more than 1 row
Anew ([1 2],:)=Anew([2 1],:);
end
Anew(1,:,:) = Anew(1,:,:).^2; %squares elements in the first row
end
I am trying to use a for loop to make some calculations in a cell array but at the end only the results for the last loop are displayed. I would like Matlab to display the results for all loops. Here there is the code:
slope=[];
time=[];
position= [];
for p=1:max(L) % max L gives the number of result{n}. so if max(L)=6 we have from result{1} to result{6} and therefore 6 final values that i want to get%
a=result{n}(:,1);
b=result{n}(:,2);
end
B = [ones(length(a),1) a] \ b % this is to obtain the slope and intercept of a lin. regresion
slope = B(2)
time = result{n}(end,1)-result{n}(1:1)
position = (slope.*result{n}(end,1)+intercept)-(slope.*result{n}(1:1)+intercept)
At the moment in the output that is what i get:
slope =
4.4089
time =
0.5794
position =
2.5546
This result is correct. However, these values are the ones obtained with result{6} and i need the values previous to this one.
Any help is much appreciated !
Thanks in advance!
You are making a mess with the indexes… It is a bit hard to understand what you did on your code, but it may be something like this (pseudocode since the code you gave does not have the result declared):
slope=zeros(1,max(L)); % Pre allocate zeros, one index for each interation
time=zeros(1,max(L));
position=zeros(1,max(L));
a=zeros(1,max(L));
b=zeros(1,max(L));
for p=1:max(L) % max L gives the number of result{n}. so if max(L)=6 we have from result{1} to result{6} and therefore 6 final values that i want to get%
a(p)=result{p}(:,1);
b(p)=result{p}(:,2);
B = [ones(length(a( p ),1) a( p )] \ b( p) % this is to obtain the slope and intercept of a lin. regresion
slope( p) = B(2)
time( p) = result{p}(end,1)-result{p}(1:1)
position( p) = (slope( p ).*result{p}(end,1)+intercept)-(slope ( p) .*result{p}(1)+intercept)
end
position(6) will get your value, position(5) the previous value.
The easiest way to do this is to remove the ";" for lines that you want printed to the command window. This will display all loop values you need.
for p=1:max(L)
a=result{n}(:,1)
b=result{n}(:,2)
end
Can you do all calculations inside the loop and don't block with ";" instead. If you get a result after coming out of a loop, you will only get the last one.
I have one program that has function and the problem, return value, it has too many output.
Like exempley: y = text the answer comes up
Error in text (line 2)
if nargin == 0
Output argument "array" (and maybe others) not assigned during call to "
C:\Users\name\Documents\MATLAB\text.m>text".
The program text.m reads a txt file that contains a couple of names and numbers like
exemple:
John doughlas 15986
Filip duch 357852
and so on. The program convert them to 15986 Doughlas John and so on.
function array = text(~)
if nargin == 0
dirr = '.';
end
answer = dir(dirr);
k=1;
while k <= length(answer)
if answer(k).isdir
answer(k)=[];
else
filename{k}=answer(k).name;
k=k+1;
end
end
chose=menu( 'choose file',filename);
namn = char(filename(chose));
fid = fopen(namn, 'r');
R = textscan(fid,'%s %s %s');
x=-1;
k=0;
while x <= 24
x = k + 1;
All = [R{3}{x},' ',R{1}{x},' ',R{2}{x}];
disp(All)
k = k + 1;
end
fclose(fid);
Is there anyway to fix the problem without starting over from scratch?
Grateful for all the answers!
You specify the function output argument in the definition, but you don't assign anything to it in the function body.
For example, in
function y = student(j)
your output is y. So you have to assign something to y.
Read more about functions in MATLAB.
Here is a working example.
The first part is to create a function called 'functionA' in a filename 'functionA.m'. Then put the following code inside:
function result = functionA(N,alpha)
result = 5;
return
end
The second part is to create another Matlab file(i.e. upto you to name it) or you can use the Matlab command window even. Then run the following code:
getresult = functionA(100,10);
getresult
After running you get the following answer:
ans =
5
The code below gives me error = Subscript indices must either be real positive integers or logicals.Because the first index using FIND function is i=1, the i-1 gives negative value. How to ignore when i==1 without using the LOOP function
fid=fopen('data.txt');
A=textscan(fid,'%f%f%f%f');
fclose(fid);
in = cell2mat(A);
i = find(in(1:end,2)>20 & in(1:end,2) <50);
out=in;
s(i)=sqrt((out(i,3)-out(i-1,3))*(out(i,3)-out(i-1,3))+(out(i,4)-out(i-1,4))*(out(i,4)-out(i-1,4)));
fid = fopen('newData.txt','wt');
format short g;
fprintf(fid,'%g\t%g\t%g\t%g\n',out',s'); %'# Write the data to the file
fclose(fid);
you can try something like this:
i = find(in(1:end,2)>20 & in(1:end,2) <50);
i = i(find( i > 1));
By the way, be careful of using i as a regular variable because you're overriding the default value of:
i = sqrt(-1)