How to store values from a loop?

5 次查看（过去 30 天）
Edward Apraku
Edward Apraku 2023-6-14
回答： Naman 2023-6-14
I have a code that loops through multiple DTA text files and graphs them together. I want to save the average value of V_f from each iteration but am currently stuck becuase it keeps overwriting and only saves the average V_f from the last DTA file.
clear all; clc; close all;
[filename,pathname]=uigetfile('*.DTA','MultiSelect','on');
numCPs=length(filename);
if numCPs>10
numCPs=1;
end
figure
ax=axes;
ax.Box='on';
ax.LineWidth=1.5;
ax.XAxis.FontSize=20; ax.XLabel.FontSize=20;
ax.YAxis.FontSize=20; ax.YLabel.FontSize=20;
hold on
for count=1:1:numCPs
if numCPs>1
CPdata=importdata(fullfile(pathname,filename{count}),' ');
else
CPdata=importdata(fullfile(pathname,filename),' ');
end
temp=strsplit(CPdata{15});
endIndex=length(CPdata);
for i=1:length(CPdata)
temp=strsplit(CPdata{i});
if temp{1}=="CURVE"
startIndex=i+3;
end
endIndex=i-1;
end
data=[];
for i=startIndex:endIndex
temp=strsplit(CPdata{i});
data=[data;str2num(temp{3}),str2num(temp{4})];
end
Time=data(:,1); %time
V_f=data(:,2); %ohm
V_favg=mean(data(:,2));
if numCPs>1
plot(Time,V_f,'-o','MarkerSize',2,'LineWidth',3,'DisplayName',filename{count});
else
plot(Time,V_f,'-o','MarkerSize',2,'LineWidth',3,'DisplayName',filename);
end
xlabel("Time (s)"); ylabel("V_f (V vs. Ref.)");
end
legend('AutoUpdate','off');
axis square;
axis([0 7200 0 10])
hold off
  1 个评论
Stephen23
Stephen23 2023-6-14
Note that you can replace this fragile code:
numCPs=length(filename);
if numCPs>10
numCPs=1;
end
..
for count=1:1:numCPs
if numCPs>1
CPdata=importdata(fullfile(pathname,filename{count}),' ');
else
CPdata=importdata(fullfile(pathname,filename),' ');
end
..
end
with this simpler and much more robust code:
filename = cellstr(filename);
..
for count = 1:numel(filename)
CPdata = importdata(fullfile(pathname,filename{count}),' ');
..
end

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采纳的回答

Sanskar
Sanskar 2023-6-14
From your question I got that you want to get all the average value but it overwrites the previous one.
Since, in the following line you are updating the V_favg in every iteration so it overwrites.
V_favg=mean(data(:,2));
To store the average value, you can create an empty 1-D array, before you start the loop and you can append the average value from every iteration to that array.
....
ax.LineWidth=1.5;
ax.XAxis.FontSize=20; ax.XLabel.FontSize=20;
ax.YAxis.FontSize=20; ax.YLabel.FontSize=20;
hold on
V_favg = []; % initialize empty array
for count = 1:1:numCPs
...
...
Time=data(:,1); %time
V_f=data(:,2); %ohm
V_favg(end+1)=mean(data(:,2)); %Appending to initialized array
if numCPs>1
plot(Time,V_f,'-o','MarkerSize',2,'LineWidth',3,'DisplayName',filename{count});
else
plot(Time,V_f,'-o','MarkerSize',2,'LineWidth',3,'DisplayName',filename);
end
xlabel("Time (s)"); ylabel("V_f (V vs. Ref.)");
...
...
end
Happy to help you,
Sanskar

更多回答（2 个）

Aman
Aman 2023-6-14
Hi Edward,
To save the average V_f value from each DTA file, you can create an array V_favg_all to store the average values.
Here's an updated version of your code that includes this modification:
clear all; clc; close all;
[filename,pathname]=uigetfile('*.DTA','MultiSelect','on');
numCPs=length(filename);
if numCPs>10
numCPs=1;
end
figure
ax=axes;
ax.Box='on';
ax.LineWidth=1.5;
ax.XAxis.FontSize=20; ax.XLabel.FontSize=20;
ax.YAxis.FontSize=20; ax.YLabel.FontSize=20;
hold on
V_favg_all = []; % initialize array to store average V_f values
for count=1:1:numCPs
if numCPs>1
CPdata=importdata(fullfile(pathname,filename{count}),' ');
else
CPdata=importdata(fullfile(pathname,filename),' ');
end
temp=strsplit(CPdata{15});
endIndex=length(CPdata);
for i=1:length(CPdata)
temp=strsplit(CPdata{i});
if temp{1}=="CURVE"
startIndex=i+3;
end
endIndex=i-1;
end
data=[];
for i=startIndex:endIndex
temp=strsplit(CPdata{i});
data=[data;str2num(temp{3}),str2num(temp{4})];
end
Time=data(:,1); %time
V_f=data(:,2); %ohm
V_favg=mean(data(:,2));
V_favg_all = [V_favg_all V_favg]; % append the new V_favg to the end of the V_favg_all array
if numCPs>1
plot(Time,V_f,'-o','MarkerSize',2,'LineWidth',3,'DisplayName',filename{count});
else
plot(Time,V_f,'-o','MarkerSize',2,'LineWidth',3,'DisplayName',filename);
end
xlabel("Time (s)"); ylabel("V_f (V vs. Ref.)");
end
legend('AutoUpdate','off');
axis square;
axis([0 7200 0 10])
hold off
The average of each iteration is stored in the V_favg_all array.
Hope this Helps!
Naman
Naman 2023-6-14
Hi Edward,
Here you are overriding the V_favg value with every iteration of for loop
V_favg=mean(data(:,2));
Instead create an array V_favg initially outside the for loop.
% Declaring V_favg2 vector outside the for loop.
V_favg = zeros(1,numCPs) ;
and keep storing average of V_f in it with each iteration of for loop.
% saving the average value of V_f from each iteration into V_favg array
V_favg(count) = mean(data(:,2)) ;
Hope it will help you.

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