Importing xlsx files - columns of unknown length

I am currently attempting to plot 4 graphs from the results of multiple trials (an example of 4 trial file names shown below). My main issue is (I believe) that columns A and B are not the same size for all of the files. I am commonly faced with 'Subscripted assignment dimension mismatch'. I am very new to Matlab, and have had some help so far getting to the stage I am at, really need some help to quickly process some data

Any help is much appreciated.

filename = {'T1_B1_P4_R1_I2_ER1_EX3_S_3.xlsx';...
    'T1_B2_P4_R1_I2_ER1_EX3_S_3.xlsx';...
    'T1_B3_P4_R1_I2_ER1_EX3_S_3.xlsx';...
    'T1_B4_P4_R1_I2_ER1_EX3_S_3.xlsx'};

col = {'r','g','b','k'};
figure; 
hold on;
for i = 1:length(filename)    
    data(:,2*i-1:2*i) = xlsread(filename{i}, 2, 'A1:B400');   
    temp = data(:,2*i-1:2*i);    
    hold on    
    plot(data(:,2*i),data(:,2*i-1),col{i});
end

Answer 1

[Image Analyst]

Don't use indexes, just suck up the whole thing:

data = xlsread(filename{i}, 2, 'A1:B400');

It will resize data each time to be the size it needs to be.

[Ben]

Although this allowed for all of my data to be plotted, it prevented the plot from being colour coded.

I really am a novice at matlab..

[Image Analyst]

I have nothing to go on.....

[Ben]

Yeah I know, I'm not having a go at all, I'm more annoyed that I can't work out what I'm doing wrong. Your help is appreciated

[Image Analyst]

I meant that you didn't attach the 4 workbooks so no one can try anything. Maybe try this:

filename = {'T1_B1_P4_R1_I2_ER1_EX3_S_3.xlsx';...
    'T1_B2_P4_R1_I2_ER1_EX3_S_3.xlsx';...
    'T1_B3_P4_R1_I2_ER1_EX3_S_3.xlsx';...
    'T1_B4_P4_R1_I2_ER1_EX3_S_3.xlsx'};

col = {'r','g','b','k'};
figure; 
for i = 1:length(filename)    
    data = xlsread(filename{i}, 2, 'A1');   
    x = data(:, 2);  % Extract x from column B 
    y = data(:, 1);  % Extract y from column A
    plot(x, y, col{i});
    hold on;
end

[Ben]

I just tried this, made an amendment to,

data = xlsread(filename{i}, 2, 'A1');

to data = xlsread(filename{i}, 2, 'A1:B500');

And this has plotted perfectly! Many thanks for your time! Greatly appreciated

[Image Analyst]

No problem. You're welcome. If we're done here, could you go ahead and officially mark it as Accepted? Thanks.

Answer 2

[Sean de Wolski]

The problem is that you're storing this all in one array when different columns might have different sizes.

Instead, create data to be a cell array (a container) and have each excel file stored as one element in it.

data{ii} = xlsread(etc)

temp = data{ii}

plot(temp ... etc )

Now each element of data can be variably sized.