I'm having trouble with the syntax in Matlab.
I'm trying to split an audio signal up into different segments (frames).
I would like to return the y-axis values to a matrix (each segment having its own column), and the corresponding time values with each segment having its own row.
I can't even get it to return just one single column and row pair (ie one frame). I just get returned two empty matrices. Here's my code.
function [mFrames, vTimeFrame] = Framing(vSignal,samplingRate,frameLPerc,frameshPerc)
totalTime=size(vSignal,1)/samplingRate
frameLength = totalTime*frameLPerc;
frameShift = totalTime*frameshPerc;
frameNumber =0;
check=frameLPerc;
while check<1
check = check+frameshPerc;
frameNumber=frameNumber+1;
end
start = 1;
% problem part
mFrames = vSignal(round((start:1/samplingRate:frameLength)*samplingRate));
vTimeFrame = round((start:1/samplingRate:frameLength)*samplingRate);
end
In the end I would like to be able to segment my entire signal into mFrames(i) and vTimeFrame(i) with a for-loop, but never mind that I cannot even get my function to return the first one (like I said empty matrix).
I know my segment code should be correct because I've got another script working with the same vSignal (it's a column vector by the way) that works just fine (y==vSignal):
voiced = y(round((1.245:1/Fs:1.608)*Fs));
plot(1.245:1/Fs:1.608,voiced)
I titled this with syntax problems because I'm very new to matlab and am used to Java. It feels very weird not initializing anything, and so I'm unsure whether my code is actually making any sense.
When testing I enter [m1,m2]=Framing(y,16000,0.1,0.05).
I got it.
start was not in the right domain. This is correct:
round((start/samplingRate:1/samplingRate:frameLength)*samplingRate)
When I plot(m2,m1) I now get the correct answer.
I do still have another question though, how can I assign these segments to my matrices?
for i=1:frameNumber
mFrames(:,i) = vSignal(round((start/samplingRate:1/samplingRate:frameLength)*samplingRate));
vTimeFrame(i) = round((start/samplingRate:1/samplingRate:frameLength)*samplingRate);
start=start+frameShift;
frameLength=frameLength+frameShift;
end
I get this error
In an assignment A(I) = B, the number of elements in B and I must be the same.
Like I said I'm trying to get the y-axis numbers in columns next to each other and the x-axis in rows.
Related
I am attempting to return the mean of non zero elements in each column in my matrix;
my first attempt was:
i = 1:peopleCount;
nonZero1(i,:) = mean(nonzeros(Y(:,i)));
that returns the same result for all columns, while my second attempt:
for i = 1:peopleCount;
nonZero2(i) = mean(nonzeros(Y(:,i)));
end
returns the correct answer.
They look identical to me, but obviously, they are not.
what went wrong in my first attempt?
how can i make the first version work?
Here's a non-destructive (without changing the input matrix) and a one-liner method -
mean_col_vals = sum(Y,1)./sum(Y~=0,1)
The trick is very simple - We get the sum along each column and divide it by the number of non-zero elements which are the elements that actually contributed to the summation values. Also, since mean internally calls sum, so we are avoiding one function call overhead with this technique!
As you pointed out the nonzeros gives back a column vector, so you cannot expect multiple means, the same value is assigned to every element of nonZero1(:,i).
A possible solution without loop:
A = Y(:,i);
A(A==0) = NaN;
nonZero3 = nanmean(A,1);
I am currently processing a bunch of files that I have imported into a structure, but have hit a bump in the road while trying to loop over the data.
First of all, here is my structure:
Ice
1.1 az160, az240, az300...
1.1.2 zen15, zen30,zen45...
1.1.2.1 Data
1.1.2.2 Textdata
I am trying to extract a value from each "textdata" cell array and use it to divide a column in data of the same structure. To do so, I am looping through the structure in the following way:
az_names = fieldnames(ice)
for m = 1:numel(az_names)
snames = fieldnames(ice.(az_names{m}))
for k = 1:numel(snames)
inttime = strrep(ice.(az_names{m}).(snames{k}).textdata(9,1), 'Integration > Time (usec): ','');
inttime = strrep(inttime, ' (USB2+E00040)','');
integration = cellfun(#str2num,inttime)
line 17 ice.(az_names{m}).(snames{k}).data(:,4) = ice.(az_names{m}).(snames{k}).data(:,3)/integration
end
end
I get the following error:
Index exceeds matrix dimensions
Edit: Matlab gives me the error at line 17. If I run the code up to "integration" and also write:
ice.(az_names{m}).(snames{k}).data(:,4)
I don't get a problem, Matlab prints to screen the right number and the data column.
I thought this would loop through each field in the structure and do the operation (dividing a column of values by a number), but I seem to be missing a point here. Can anybody see my mistake?
Regards,
If the error occurs when you try to execute this fragment:
ice.(az_names{m}).(snames{k}).data(:,4)
Then the cause is quite simple.
The variables m and k seem to be handled properly (due to the numel in the loop they should never be too big), meaning that the 4 is simply too big.
Check
ice.(az_names{m}).(snames{k}).data(:,4)
Or even more directly
size(ice.(az_names{m}).(snames{k}).data)
And you should find that the second element of the size is less than 4.
On second thought, this fragment works:
a.b=1;
a.b(:,4)=1
So I suspect that the error occurs when trying to read in this part:
ice.(az_names{m}). (snames{k}).data(:,3)
Meaning that the second element of the size should even be less than 3.
Also I would recommend removing the space.
Hi and thank you for viewing my question.
I have a large spreadsheet (over 650,000 rows) that I am trying to spit up into separate parts of a structure. I am trying to split it up by the values in one of the columns of which there is 1132 unique text values. The rest of the columns are numerical. I have created a matrix of the numerical values with 4 columns called 'SectionID_Matrix' and a cell array for the text column I want to split the data up by called 'ELR'. I am also trying to name the parts in the structure by the text value I have split them up by. My code is as follows:
ELR_list = unique (ELR);
[m,~]=size(ELR_list);
n = 1;
b = [];
for j = 1:m
x = strcmp(ELR_list(n), char(ELR));
b(:,1) = SectionID_Matrix(x(:,1),1);
b(:,2) = SectionID_Matrix(x(:,1),2);
b(:,3) = SectionID_Matrix(x(:,1),3);
b(:,4) = SectionID_Matrix(x(:,1),4);
t = char(ELR_list(n));
s.(t) = b;
n = n+1;
end
clearvars -except *ELR_list* *ELR* *SectionID_Matrix* *s*
When I run this code though I get an error saying 'Subscripted assignment dimension mismatch'. Error in Sorting_Out_Locations (line 10). b(:,1) = SectionID_Matrix(x(:,1),1);
This is confusing me because when I remove the for loop and manually change the value of n, it works perfectly fine giving me a matrix in the structure with all the rows that contain the nth text value with the name of the text value.
I understand the error is caused by attempting to assign more elements to a section of a matrix or vector than that section can hold but I don't understand where that is happening.
Is there an error in my code that is causing the for loop to fail? because from my limited understanding the loop should just keep going around increase n by 1 each time until it has gone through all of the unique ELR values.
This is my very first time on Matlab (so any pointer on my code are very appreciated) and have spend all afternoon trying to get this working but no amount of internet help or the matlab website is helping.
Thank you for any help
In your code, the first time it runs through the loop, the size of the b matrix is set according to the number of true values in x. The next time it runs through the loop, that may be a different size, so you get the mismatch.
You can just clear b at the end of each loop iteration with b = []
The error Subscripted assignment dimension mismatch appears when you try to insert a matrix of a certain size into a matrix of a different size. For your code, it means that in the line
b(:,1) = SectionID_Matrix(x(:,1),1);
there is an attempted insertion of mismatching sizes: the size of SectionID_Matrix(x(:,1),1) and the size of b(:,1) are not the same. This is most likely because you only take certain values of each column of SectionID_Matrix using the logical indexing of x. To fix this you need the same logical indexing in b:
b(x(:,1),1) = SectionID_Matrix(x(:,1),1);
I'm currently working on a cellular automata but i keep running into this problem. I have a matrix idxR which contains zero's and/or ones, depending on a probability process:
idxR = ((rRecr>rEmpty)&(rRecr>rAlgae)&(rRecr>rCoral));
Now i want to replace all ones in idxR with unique values and assign it to the variable colonies. I came up with the following:
colonies = idxR;
no = sum(colonies(:)==1)
maxvalue = max(colonies(:));
replace = [1:no]+maxvalue;
ret = reshape(replace,no,1);
colonies(colonies==1) = colonies(colonies==1).*ret;
When i output colonies it gives me a matrix with just ones and zeros and not a matrix where all ones have been replaced with incremental values. I tried this code in a new file and assigned a matrix with random ones and zeros to idxR and then it seems to work. So i guess to problem lies with the matrix idxR in my automata. It might be worth mentioning that idxR is contained in a for loop.
Can somebody tell me how to fix this?
You got the entire logic correct, except one minor flaw. You have idxR as a logical matrix. Hence colonies is a logical matrix too. Therefore, you get the expected output till the second-last line. Problem occurs on the last line, when you try to assign an array of numbers in which each number is greater than 1 (colonies(colonies==1).*ret;) to a logical matrix.
Elements greater than 1 are clipped to one and thus you see only zeros and ones. There is a simple workaround. Change the first line to
colonies = double(idxR);
P.S. The answer was right in front of you, you just didn't spot it. You had written:
I tried this code in a new file and assigned a matrix with random ones and zeros to idxR and then it seems to work.
The idxR matrix must have been of double datatype, if you used randi.
Parag got it right. You have the solution there.
You can use the following code if you are looking for a more "organized" way to get to 'colonies' -
colonies = double(idxR);
maxvalue = max(colonies(:));
ind1 = find(idxR==1);
colonies(ind1)=maxvalue + (1:numel(ind1));
I have a list of text files that I would like to load, and then extract rows where they all overlap. The first column contains years and each data set spans a different chunk of years but they all overlap in the middle. In the end I would like to have a three dimensional matrix with the overlapping years in one matrix. My code keeps getting stuck at the line that I have commented out. I know its incorrect but could anyone tell me why it is incorrect?
clear all
name_list = {'Beijing';'GT';'soi';'naoi';'Sydney_Airport';'Los Angeles';'Paris';'Presque Isle'};
[m,n] = size(name_list);
files = dir('*.txt');
[m,n] = size(files);
for i=1:m
eval(['load ' files(i).name ' -ascii']);
vals{i} = load(files(i).name);
matrix = vals{i};
station = (files(i).name(1:end-4));
startyear(i) = min(matrix(:,1));
endyear(i) = max(matrix(:,1));
allstart = max(startyear);
allend = min(endyear);
%matrixnew(i) = matrix(allstart:allend,2:13,i);
end
Two problems here:
Your commented line %matrixnew(i) = matrix(allstart:allend,2:13,i); assumes that matrix is a 3-d array, but elsewhere you treat it as 2-d (and I believe that load always returns a 2-d array). This could be why you are getting the "Index exceeds matrix dimensions" error. Example:
>> foo = rand(10,10);
>> foo(2:10,3:4,2)
Index exceeds matrix dimensions.
Maybe you want matrix(allstart:allend,2:13)? But that won't work, because allstart contains a year, which presumably will not be a valid index for the array (a more likely cause of your error). Using the index that contains the smallest value would be closer to being correct, but I think it still won't work.
matrixnew refers to a single element of an array. You can't assign an array to an element of an array. grantnz is right that making matrixnew a cell array would fix this error, and I guess that in the end you could turn your cell array into 3-d array.
I think you are on the right track, but are missing a few pieces to making this work. One thing to consider is that it looks like you are trying to do everything in a single pass. I don't see how that can work. You need to real all files before you can decide which range of years to keep. So do it in multiple passes: first load all data from all files into a cell array, then figure out the range of years, then pull the data from each file for that range of years.