I have a loop which runs 100 times. In each iteration there is a string, double and a table assigned, and in the next iteration new values are assigned for them. What I want to do is to accumulate these values and after the loop finishes save the total result as result.mat using the matlab save function. I've tried putting them in cell-array but its not working so far, so if anyone could please advise how this can be done.
This is what I did:
results_cell=(100,3);
.
.
.
results_cell(i,1)=stringA;
results_cell(i,2)=TableA;
results_cell(i,3)=DoubleA;
But it gives this error Coversion to Cell from Table is not possible. So I've tried converting TableA to array of Doubles using table2array but I still get this Coversion to Cell from Double is not possible
I think using a structure would be a good way to store your data, since they are of different types and you can assign it meaningful field names for easy reference.
For example, let's call the structure Results. You can initialize it like so.
Results = struct('StringData',[],'TableData',[],'DoubleData',[])
Since you know its dimensions, you can even do this:
N = 100;
Results(N).StringData = [];
Results(N).TableData = [];
Results(N).DoubleData = [];
This automatically create a 1xN structure with 3 fields.
Then in your loop you can assign each field with its associated data like so:
for k = 1:N
Results(k).StringData = String(k);
Results(k).TableData = Table(k);
Results(k).DoubleData = Double(k);
end
where String(k), Table(k) and Double(k) are just generic names for your actual data.
When you're done with the loop you can access any type of data using a single index and the right field name.
In order to save a .mat file, use something like this:
save SomeFileName.mat Results
Which you can load into the workspace as you would with any .mat file:
Eg:
S = load('SomeFileName.mat')
R = S.Results
Hope that helps!
Related
I need to pass a part of a structure's name into a function.
Examples of a available structs:
systems.system1.stats.equityCurve.relative.exFee
systems.system1.stats.equityCurve.relative.inFee
systems.system2.stats.equityCurve.relative.exFee
systems.system2.stats.equityCurve.relative.inFee
systems.system1.returns.aggregated.exFee
systems.system1.returns.aggregated.inFee
systems.system2.returns.aggregated.exFee
systems.system2.returns.aggregated.inFee
... This goes on...
Within a function, I loop through the structure as follows:
function mat = test(fNames)
feeString = {'exFee', 'inFee'};
sysNames = {'system1', 'system2'};
for n = 1 : 2
mat{n} = systems.(sysNames{n}).stats.equityCurve.relative.(feeString{n});
end
end
What I like to handle in a flexible way within the loop is the middle part, i.e. the part after systems.(sysNames{n}) and before .(feeString{n}) (compare examples).
I am now looking for a way to pass the middle part as an input argument fNames into the function. The loop should than contain something like
mat{n} = systems.(sysNames{n}).(fName).(feeString{n});
How about using a helper function such as
function rec_stru = recSA(stru, field_names)
if numel(field_names) == 1
rec_stru = stru.(field_names{1});
else
rec_stru = recSA(stru.(field_names{1}), field_names(2:end));
end
This function takes the intermediate field names as a cell array.
This would turn this statement:
mat{n} = systems.(sysNames{n}).stats.equityCurve.relative.(feeString{n});
into
mat{n} = recSA(systems.(sysNames{n}), {'stats', 'equityCurve', 'relative', feeString{n}});
The first part of the cell array could then be passed as an argument to the function.
This is one of those cases where matlab is a bit unhelpful in the documentation. There is a way to use the fieldnames function in matlab to get the list of all the fields and iterate over that using dynamic fields.
systems.system1.stats.equityCurve.relative.exFee='T'
systems.system1.stats.equityCurve.relative.inFee='E'
systems.system2.stats.equityCurve.relative.exFee='S'
systems.system2.stats.equityCurve.relative.inFee='T'
systems.system1.returns.aggregated.exFee='D'
systems.system1.returns.aggregated.inFee='A'
systems.system2.returns.aggregated.exFee='T'
systems.system2.returns.aggregated.inFee='A'
dynamicvariable=fieldnames(systems.system1)
This will return a cell matrix of the field names which you can use to iterate over.
systems.system1.(dynamicvariable{1})
ans =
equityCurve: [1x1 struct]
Ideally you would have your data structure fixed in such a way that you know how many levels of depth are in your data structure.
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 a large amount of .csv files from my experiments (200+) and previously I have been reading them in seperately and also for later steps in my data handling this is tedious work.
co_15 = csvread('CO_15K.csv',5,0);
co_25 = csvread('CO_25K.csv',5,0);
co2_15 = csvread('CO2_15K.csv',5,0);
co2_80 = csvread('CO2_80K.csv',5,0);
h2o_15 = csvread('H2O_15K.csv',1,0);
etc.....
So I want to make a cell at the beginning of my code looking like this and then a for loop that just reads them automatically.
input = {'co_15' 5;'co_25' 5;...
'co2_15' 5; 'co2_80' 5;...
'h2o_15' 1; 'h2o_140' 1;...
'methanol_15' 5;'methanol_120' 5;'methanol_140' 5;...
'ethanol_15' 5;'ethanol_80' 1;'ethanol_140' 5;...
'co2_ethanol_15' 5 ;'co2_ethanol_80' 5;...
'h2o_ethanol_15' 1 ;'h2o_ethanol_140' 1;...
'methanol_ethanol_15' 5;'methanol_ethanol_120' 5;'methanol_ethanol_140' 5};
for n = 1:size(input,1)
input{n,1} = csvread(strcat(input{n,1},'k.csv'),input{n,2},0);
end
The cell in this code is 19 rows and 2 columns, the rows are all the files and the columns will contain the parameters to handle the data. Now the problem I can't find a solution for is that my first column is a string name and I want that string name to be the name of the variable where csvread writes its data to but the way I set it up now it just overwrites the string in the first column of the cell with the csv data. To be extra clear I want my matlab workspace to have variables with string names in the first column containing the data of my csv files. How do I solve this?
You don't actually want to do this. Even the Mathworks will tell you not to do this. If you are trying to use variable names to keep track of related data like this, there is always a better data structure to hold your data.
One way would be to have a cell array
data = cell(size(input(:,1)));
for n = 1:size(input,1)
data{n} = csvread(strcat(input{n,1},'k.csv'),input{n,2},0);
end
Another good option is to use a struct. You could have a single struct with dynamic field names that correspond to your data.
data = struct();
for n = 1:size(input,1)
data.(input{n,1}) = csvread(strcat(input{n,1},'k.csv'),input{n,2},0);
end
Or actually create an array of structs and hold both the name and the data within the struct.
for n = 1:size(input, 1)
data(n).name = input{n,1};
data(n).data = csvread(strcat(input{n,1},'k.csv'),input{n,2},0);
end
If you absolutly insist on doing this (again, it's is very much not recommended), then you could do it using eval:
for n = 1:size(input, 1)
data = csvread(strcat(input{n,1},'k.csv'),input{n,2},0);
eval([input{n, 1}, '= data;']);
end
Is it possible to refer back to/access the names of variables (say nx1 arrays) that make up a matrix? I wish to access them to insert there names into a plot or figure (as a text) that I have created. Here is an example:
A = [supdamp, clgvlv,redamp,extfanstat,htgvlv,occupied,supfanspd]
%lots of code here but not changing A, just using A(:,:)'s
%drawn figure
text(1,1,'supdamp')
...
text(1,n,'supfanspd')
I have failed in an attempt create a string named a with their names in so that I could loop through a(i,1), then use something like text(1,n,'a(i,1)')
Depending on your problem, it might make sense to use structures with dynamical field names.
Especially if your data in the array have some meaning other than just entries of a matrix in linear algebra sense.
# name your variables so that your grandma could understand what they store
A.('supdamp') = supdamp
A.('clgvlv') = clgvlv
...
fieldsOfA = fieldnames(a)
for n = 1 : numel(fieldsOfA )
text(1, n, fieldsOfA{n})
end
I need to output .mat files for the below data. I need one file to have cell (1,1) to be Mean_RPM_list1, cell (2,1) to be Mean_RPM_list2 etc. And then I need another file to have cell(1,1) to be Mean_Torque_list1 to have cell(1,1).....and so on.
Can anybody shed any light on this for me?
Also if someone knows how to automate me calling the matrices A and B so I could have A = [Mean_rpm1:Mean_rpmMAX], that would also be very helpful.
TIA for any help.
A = [Mean_rpm1 Mean_rpm2 Mean_rpm3 Mean_rpm4 Mean_rpm5 Mean_rpm6 Mean_rpm7 Mean_rpm8 Mean_rpm9 Mean_rpm10 Mean_rpm11 Mean_rpm12];
B = [Mean_torque1 Mean_torque2 Mean_torque3 Mean_torque4 Mean_torque5 Mean_torque6 Mean_torque7 Mean_torque8 Mean_torque9 Mean_torque10 Mean_torque11 Mean_torque12];
plot(A,B,'*')
for i = 1:num_bins;
bin = first + ((i-1)/10);
eval(sprintf('Mean_RPM_list%0.f = A;',bin*10));
eval(sprintf('Mean_Torque_list%0.f = B;',bin*10));
end
First of all this is really bad idea to create a set of variables with names different by numbers. As you can see it's very difficult to deal with such variables, you always have to use eval (or other related) statements.
It's much easier to create a cell array Mean_rpm and access its elements as Mean_rpm{1}, etc.
If the vectors are numeric and have the same size you can also make a 2D/3D array. Then access as Mean_rpm(:,:,1) etc.
Next, to store a cell array to a mat-file you have to create this array in MATLAB. No options (at least for now) to do it by parts in a loop. (But you can do it for numeric vectors and matrices using matfile object.) So why do you need this intermediate Mean_RPM_list variable? Just do Mean_RPM_list{bin*10} = A in your loop.
For your first question, if you already have those variables you have to use eval in a loop. Something like
A = [];
for k=1:K
eval(sprintf('A{k} = [A, Mean_rpm%d];',k));
end
You can also get names for all similar variables and combine them.
varlist = who('Mean_rpm*');
A = cell(1,numel(varlist);
for k = 1:numel(varlist)
eval('A{k} = varlist{k};');
end
Here is one without loop using CELL2FUN:
A=cellfun(#(x)evalin('base',x),varlist,'UniformOutput',0);
You should avoid having all these individual variables around in the first place. Data types like arrays, cell arrays and structure arrays exist to help you with this. If you want each variable to be associated with a name, you can use a structure array. I've made an example below. Instead of assigning a value to Mean_rpm1 like you are doing now, assign it to meanStruct.Mean_rpm1 then save the entire structure.
% as you generate values for each variable, assign them to the
% appropriate field.
meanStruct.Mean_rpm1 = [10:10];
meanStruct.Mean_rpm2 = [12:15];
meanStruct.Mean_rpm3 = [13:20];
meanStruct.Mean_rpm4 = [14];
meanStruct.Mean_rpm5 = [15:18];
meanStruct.Mean_rpm6 = [16:20];
meanStruct.Mean_rpm7 = [17:22];
meanStruct.Mean_rpm8 = [18:22];
meanStruct.Mean_rpm9 = [19:22];
meanStruct.Mean_rpm10 = [20:22];
meanStruct.Mean_rpm11 = [21:22];
meanStruct.Mean_rpm12 = [22:23];
% save the structure array
save('meanValues.mat','meanStruct')
% load and access the structure array
clear all
load('meanValues.mat')
temp = meanStruct.Mean_rpm3