I would like to use a dataset filename "AUDUSD" in several functions. It would be easier for me, just to change the filename "AUDUSD" to a more general name like "FX" and then using the abbreviation "FX" in other_matlab functions, e.g. double(). But matlab does not know the name "FX" (that should be assigned to the dataset "AUDUSD") in the code below... Any suggestions?
CODE:
FX = 'AUDUSD';
load(FX); %OKAY !!! FX works as input to open file AUDUSD!
Svars = {'S_bid','S_offer'};
Fvars = {'F_bid','F_offer'};
vS = double(FX,Svars); % FX does NOT work as input for the file AUDUSD
There is no double() function that accepts multiple cell arrays as arguments (this is what happens when you call double(FX,Svars)).
If you call double(FX), then each character in FX is interpreted for its ASCII value and then cast to double. So you get [ 65.0 85.0 68.0 85.0 83.0 68.0 ]. This is the behavior for the double() function if you provide a vector: each individual value in the vector is cast to double.
You'd have to provide more details on what you're trying to accomplish to give any more suggestions.
I have a different example, maybe you will better understand my point. The key work I would like to process is as follows:
I have got a folder with "dataset" files. I would like to loop through this folder, entering in any datasetfile, extracting the 2nd and 3rd column of each dataset file, and constructing only ONE new datasetfile with all 2nd and 3rd columns of the datasetfiles.
One problem is that the size of the datasetfiles are not the same, so I tried to translate a datasetfile into a double-matrix and then consolidate all double matrices into ONE double matrx.
Here my code:
folder_string = 'Diss_Data/Raw';
FolderContent = dir(folder_string);
No_ds = numel(FolderContent);
for i = 1:No_ds
if isdir(FolderContent(i).name)==0
file_string = FolderContent(i).name;
file_path = strcat(folder_string,'/',file_string)
dataset_filename = file_string(1:6);
load(file_path); %loads the suggested datasetfile; OKAY
M = double(dataset_filename);% returns an ASCII code number; WRONG; should transfer the datasetfile into a matrix M
vS = M(:,2:3);
%... to be continued
end
end
Related
I am importing data from a .mat file and then extracting certain signals from it and I call this data, data. data is a 1x1 struct with 1 field, FT_est_X, where X is the the particular run that I collected the samples from. Here is the code snippet of how I do that.
data = load('site_data_all_2.mat');
t = data.FT_est_2.time;
% estimated data
Fx = data.FT_est_2.signals(1).values;
Fy = data.FT_est_2.signals(2).values;
Fz = data.FT_est_2.signals(3).values;
Mx = data.FT_est_2.signals(4).values;
My = data.FT_est_2.signals(5).values;
Mz = data.FT_est_2.signals(6).values;
So, you can see that this data was collected from run 2. Now, let's say I want to load in a file named site_data_all_3.mat (run 3), what happens is that all the data below %estimated data changes its name--everything stays the same, except the 2 becomes a 3 (e.g. Fx would be Fx = data.FT_est_3.signals(1).values;. Currently, I have to manually enter in the 3 for each variable; can anyone tell me how I can only change the file name and it will automatically change the variable names for me? Essentially, I just want it to be Fx = data.name_of_struct_field.signals(1).values.
Thank you!
You could construct the string some programmatic way (maybe with an iteration variable), but here's the simple answer of defining the fieldname as a string and simply using it. At the next iteration, update the fieldname variable and repeat.
fieldname = 'FT_est_2';
Fx = data.(fieldname).signals(1).values;
Consider the arbitrary function:
function myFunc_ = myFunc(firstInput, secondInput)
myFunc_ = firstInput * secondInput;
end
Now imagine I want to map the above function to an array for the first input firstInput, while the second input secondInput is constant. For example, something like:
firstVariable = linspace(0., 1.);
plot(firstVariable, map(myFunc, [firstVariable , 0.1]))
where 0.1 is an arbitrary scalar value for the secondInput and firstVariable array is an arbitrary array for the firstInput.
I have looked into the arrayfun() function. However, I don't know how to include the constant variable. Plus it seems like the syntax between MATLAB and Octave are different, or maybe I'm mistaken. It is important for me to have a cross-compatible code that I can share with colleagues.
Assuming in the original function you were multiplying two scalars and you want to vectorise, then
function myFunc_ = myFunc(firstInput, secondInput)
myFunc_ = firstInput .* secondInput;
end
should work just fine.
Then plot it directly:
plot( firstVariable, myFunc(firstVariable , 0.1) )
I'm afraid the arbitrary examples given in the original question were too simplified and as a result, they do not represent the actual issue I'm facing with my code. But I did manage to find the right syntax that works inside Octave:
plot(firstVariable, arrayfun(#(tempVariable) myFunc(tempVariable, 0.1), firstVariable))
basically the
#(tempVariable) myFunc(tempVariable, 0.1)
creates what is so-called an anonymous function and the
arrayfun(<function>, <array>)
maps the function over the given array.
I have an excel file and I need to read it based on string values in the 4th column. I have written the following but it does not work properly:
[num,txt,raw] = xlsread('Coordinates','Centerville');
zn={};
ctr=0;
for i = 3:size(raw,1)
tf = strcmp(char(raw{i,4}),char(raw{i-1,4}));
if tf == 0
ctr = ctr+1;
end
zn{ctr}=raw{i,4};
end
data=zeros(1,10); % 10 corresponds to the number of columns I want to read (herein, columns 'J' to 'S')
ctr=0;
for j = 1:length(zn)
for i=3:size(raw,1)
tf=strcmp(char(raw{i,4}),char(zn{j}));
if tf==1
ctr=ctr+1;
data(ctr,:,j)=num(i-2,10:19);
end
end
end
It gives me a "15129x10x22 double" thing and when I try to open it I get the message "Cannot display summaries of variables with more than 524288 elements". It might be obvious but what I am trying to get as the output is 'N = length(zn)' number of matrices which represent the data for different strings in the 4th column (so I probably need a struct; I just don't know how to make it work). Any ideas on how I could fix this? Thanks!
Did not test it, but this should help you get going:
EDIT: corrected wrong indexing into raw vector. Also, depending on the format you might want to restrict also the rows of the raw matrix. From your question, I assume something like selector = raw(3:end,4); and data = raw(3:end,10:19); should be correct.
[~,~,raw] = xlsread('Coordinates','Centerville');
selector = raw(:,4);
data = raw(:,10:19);
[selector,~,grpidx] = unique(selector);
nGrp = numel(selector);
out = cell(nGrp,1);
for i=1:nGrp
idx = grpidx==i;
out{i} = cell2mat(data(idx,:));
end
out is the output variable. The key here is the variable grpidx that is an output of the unique function and allows you to trace back the unique values to their position in the original vector. Note that unique as I used it may change the order of the string values. If that is an issue for you, use the setOrderparameter of the unique function and set it to 'stable'
I have some data in a .txt file. that are separated by commas.
for example:
1.4,2,3,4,5
2,3,4.2,5,6
24,5,2,33.4,62
what if you want the average of columns, like first column (1.4,2 and 24)? or second column(2,3 and 5)?
I think putting the column in an array and using the built in mean function would work, but so far, I am only able to extract rows, not columns
instead of making another thread, I thought i'd edit this one. I am working on getting the average of each column of the well known iris data set.
I cut a small portion of the data:
5.1,3.5,1.4,0.2,Iris-setosa
4.9,3.0,1.4,0.2,Iris-setosa
4.7,3.2,1.3,0.2,Iris-setosa
4.6,3.1,1.5,0.2,Iris-setosa
5.0,3.6,1.4,0.2,Iris-setosa
5.4,3.9,1.7,0.4,Iris-setosa
4.6,3.4,1.4,0.3,Iris-setosa
delimiterln= ',';
data = importdata('iris.txt', delimiterln);
meanCol1 = mean(data(:,1))
meanCol2 = mean(data(:,2))
meanCol3 = mean(data(:,3))
meanCol4 = mean(data(:,4))
Undefined function 'sum' for input arguments of type 'cell'.
Error in mean (line 115)
y = sum(x, dim, flag)/size(x,dim);
Error in irisData(line 6)
meanCol1 = mean(data(:,1))
it looks like there is an error with handling data type...any thoughts on this? I tried getting rid of the last column, which are strings. and it seems to work without error. So i am thinking that it's because of the strings.
Use comma separated file reading function:
M = csvread(filename);
Now you have the matrix M:
col1Mean=mean(M(:,1));
I have the following example which expresses the type of problem that I'm trying to solve:
clear all
textdata = {'DateTime','St','uSt','Ln','W'};
data = rand(365,4);
Final = struct('data',data,'textdata',{textdata})
clear textdata data
From this, Final.data contains values which correspond to the headings in Final.textdata excluding the first ('DateTime') thus Final.data(:,1) corresponds to the heading 'St'... and so on. What I'm trying to do is to create a variable in the workspace for each of these vectors. So, I would have a variable for St, uSt, Ln, and W in the workspace with the corresponding values given in Final.data.
How could this be done?
Will this solve your problem:
for ii=2:length( textdata )
assignin('base',Final.textdata{ii},Final.data(:,ii-1));
end
Let me know if I misunderstood.
The direct answer to your question is to use the assignin function, like so (edit: just like macduff suggested 10 minutes ago):
%Starting with a Final structure containing the data, like this
Final.textdata = {'DateTime','St','uSt','Ln','W'};
Final.data = rand(365,4);
for ix = 1:4
assignin('base',Final.textdata{ix+1}, Final.data(:,ix));
end
However, I strongly discourage using dynamic variable names to encode data like this. Code that starts this way usually ends up as spaghetti code full of long string concatenations and eval statements. Better is to use a structure, like this
for ix = 1:4
dataValues(Final.textdata{ix+1}) = Final.data(:,ix);
end
Or, to get the same result in a single line:
dataValues = cell2struct(num2cell(Final.data,1), Final.textdata(2:end),2)