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I have two arrays the first one represents the time axis with time stamp 1 min
time=[0,60,60,120,180,240,300,360,420,480,540]
and the second array represents a data values as follows
data=[18,12,12,0,7,9,6,8,12,18,0]
what im trying to do is two things:
1-I would like to fix the time axis to have 1 second time stamp
2-Perform linear Interpolation as follows:
for example i have
enter image description here
and i would like to have sth like this:
enter image description here
In case of time repetation like the repated 60 seconds the duplication should be deleted
You can remove duplicates (the first value is kept) with
time = [0,60,60,120,180,240,300,360,420,480,540];
data = [18,12,12,0,7,9,6,8,12,18,0];
[time_u unique_indeces] = unique(time);
data_u = data(unique_indeces);
clear unique_indeces;
and interpolate with
time_i = linspace(min(time), max(time), max(time) - min(time) + 1);
data_i = interp1(time_u, data_u, time_i);
I prefer linspace because I usually want to set the number of data points and not the space between points but you can also use min(time):max(time) or time(1):time(end) instead.
This code will also sort your data points by time.
Function interp1 does the job:
time=[0,60,120,180,240,300,360,420,480,540];
data=[18,15,0,7,9,6,8,12,18,0];
time_1s = 0:540;
data_interpd = interp1(time, data, time_1s);
Note: I have manually deleted the first duplicate value at time 60. If there is only one value to remove (always at same place), I think the best is to remove it by using a mask, since unique removes the second occurrence of duplicates and not first one.
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I loaded in the 1000x1 .txt file but I need to make it 100x10? How do I do this in matlab?
Thanks
Reshape should do this for you. https://www.mathworks.com/help/matlab/ref/reshape.html
But you haven't explained any criteria regarding what the change of dimensions is based on. So, it may not be exactly what you want.
You can use the reshape function to do this. In the example below I created a column vector x that is 1000 x 1 containing numbers that ramp from 1 to 1000. I didn't know what order you wanted the rows and columns populated, so I created variables x2 and x3 with the two variations, you can choose the form that fits your needs.
x = (1:1000)';
% x2 is created with one column at a time
x2 = reshape(x, 100, 10);
% x3 is created one row at a time
x3 = reshape(x, 10, 100)';
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I am very new to Matlab and coding in general, so I apologize if this is a basic question.
I have a matrix of three columns (data1) where the first column refers to time (s).
I would like to make a new matrix (bout1) consisting of entire rows of the matrix data1 based on the values in the first column (so, for example, in a range from 30 s to 120 s).
I know how to extract the rows based on the row number:
bout1 = data1(361126:391643,:)
but not based on the values in a specific column.
You can use the find function (see here) to find the rows you need, like this:
time = data1(:, 1);
i = find(30 <= time & time <= 120);
bout1 = data1(i, :);
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So for my probability class, my professor asked the following question on a homework problem:
A fair coin is flipped 10,000 times. Let X correspond to the difference between the number of heads and the number of tails. Using MATLAB, compute the expected value of X.
This is what I wrote to answer the question:
N = 10000;
i =0;
r=1/2;
Q=nchoosek(N,(X+N)/2);
X=(1,N);
for i=-N:N
P=Q*r.^(X+N)/2*(1-r)^(N-(X+N)/2) % probability_mass_function
E=sum(abs(X).*P); % expected value
end
However, is there faster and quicker way to compute this expected value? Any help would be greatly appreciated. Thanks
You can put all tests results in single matrix in one line and then calculate X per test, then average over X:
clear
TAIL=0; HEAD=1;
NumTests=121;
NumRollsPerTest=10*1000;
AllTestsRolls= rand(NumTests,NumRollsPerTest)>0.5 ; %head when rand>0.5
XperTest=sum(AllTestsRolls==HEAD,2)-sum(AllTestsRolls==TAIL,2);%every row is test so calc per test
ExpectedX=sum(XperTest)/length(XperTest)
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I would like to pick two different random elements from given array with their positions. Similar like with datasample, but with datasample there is a possibility of picking the same element twice.
I could use while loop or similar, but I suppose there is an easier way to do it.
Say you have a matrix A:n by m, you can choose two elements at random as following,
A=[2 7 8;5 4 6;8 3 11];%given array
[n m]=size(A);
x=2;%two different random elements
i=randperm(n,x)%row index for x elements
j=randperm(m,x)%column index for x elements
A(i(1),j(1)) %First random element
A(i(2),j(2)) %Second random element
If you try this you could get something like,
i =
2 3
j =
2 1
ans =
4
ans =
8
the code can be further simplified but just wanted to make it clear. Please let me know if you have any additional questions or require further clarification.