plot graph from cell array

I have loaded 15 excel files into matlab and saved them all as a 15x1 cell.

My aim is to create 15 graphs, showing the contents of each row of the cell array against tim in a subplot.

I have made a for loop, which I ant to loop thorugh each doubl ein the cell array and plot against time. This does make 15 plots but I think it is plotting the same data 15 times. Would anybody be able to help?

%% load all the excel files in, using the same method as csv
files = dir('*.xlsx'); %dir lists the files in a folder. In the specified folder, recognise all the .xlsx files
num_files = length(files); %specify how many files have been found and call it num_files
grainsleft = cell(length(files), 1); %create a cell array the same length as the number of files in one column
%for all the files found in the specified folder, read the tables of data and fill the empty cell array 'results' with the data in each .xlsx file
for a = 1:num_files
  grainsleft{a} = readtable(files(a).name);
end

%% time steps
%number of xlsx files = number of time steps the model is run for (seconds)
totalruntime = 3001
time = 1:totalruntime;

%% mass efflux vs. time
%subplot all the mass efflux plots

for b = 1:length(grainsleft)
    g{b} = grainsleft{b}(:,1);
    g_array{b} = table2array(g{b});
    gl{b}= g_array{b}
end 

for c = 1:length(gl)
subplot(4,4,c)
bar(time,gl{c}(:,1), 0.01, 'EdgeColor', 'r')
hold on
end

[Adam Danz]

At quick glance it looks OK but I don't put much weigh on human-read code. If you save grainsleft to a mat file and attach it, we can run the code.

[C.G.]

Thank you for your response.

I have worked out how to do some of what I required.

I have managed to plot my 15 different graphs now. But in 'grainsleft' I have included the experiment number as the data heading at the top of each cell, e.g.'COR0.1 SC10 FC0.1'. I would like to use this experiment number to title the respective graphs. I have attached my file with the grains left saved to it.

Would you be able to help?

Answer 1

[Adam Danz]

This is the result I get and the plots are clearly different (the shape and the y-axis-limit).

For comparison, equate the axis limits using linkaxes()

ax = gobjects(size(gl));  % <-- added
for c = 1:length(gl)
    ax(c) = subplot(4,4,c);  % <-- save handles
    bar(time,gl{c}(:,1), 0.01, 'EdgeColor', 'r')
    hold on
    grid on  % <-- added
end
linkaxes(ax)  % <-- added

By the way, the script you shared could be cleaned up and reduced to,

% New version that replaces your entire script

files = dir('*.xlsx');
num_files = numel(files); 
grainsleft = cell(numel(files), 1); 
for a = 1:num_files
  grainsleft{a} = readtable(files(a).name);
end

totalruntime = 3001;
time = 1:totalruntime;
figure(); 
ax = gobjects(size(grainsleft));
for i = 1:numel(grainsleft)
    ax(i) = subplot(4,4,i);
    bar(ax(i), time, grainsleft{i}{:,1}, 0.01, 'EdgeColor', 'r')
    grid(ax(i),'on')
end
linkaxes(ax)

Lastly, consider using a histogram, or fill instead of bar. The bar plot is not representitive of your actual data. It hides important features.

fill(ax(i),[time(:);flipud(time(:))], [grainsleft{i}{:,1}(:);zeros(numel(time),1)],'r','EdgeColor','none')
% or
histogram(ax(i),'BinEdges',timeBins, 'BinCounts',grainsleft{i}{:,1},'EdgeColor','none','FaceColor','r')

Results of fill

[C.G.]

Thankyou for your help with this. The information you have provided has been very useful.

Just 1 last quesiton, in 'grainsleft' I have included the experiment number as the data heading at the top of each cell, e.g.'COR0.1 SC10 FC0.1'. I would like to use this experiment number to title the respective graphs.Is this possible, as currently I do not know which of the graphs equates to which experiment

[Adam Danz]

title(grainsleft{i}.Properties.VariableNames{1})

[C.G.]

Fantastic thank you.

I have been working my way through the cleaned up and reduced code you provided to ensure I understand it. However, I have a second set of graphs that are plotted after the fill graphs, which I cannot get to work now the variables have changed. Would you be able to help me with this?

my original code was:

%fft/power spectra 
%set up basic parameters
figure(2)
%Loop through all the files in g1 and plot the respective power spectra
for d = 1:18
signal = gl(:,d);
N = length(signal); %number of samples in the signal
fs = 100; %how many samples are taken per second
fnyquist = fs/2; %nyquist frequency
%plot a single sided power spectrum with log frequency axis
%abs is the magnitude values
%fft is a built in function that determines magnitude and phases of sinusoids present
%put number <size (grains) after signal, can change resoltuion 
%no number, matlab will do the whole length of the vector
X_mags = abs(fft(signal));
%assign frequency axis values, starting with bins from 0:N-1
bin_vals = [0 : N-1];
%to convert from bin to Hz use the standard formula: bin*fs/N, where fs and
%N are defined at the beginning
fax_Hz = bin_vals*fs/N;
%ceil rounds N/2 to the nearest integer greater or equal to that element; e.g. -1.9 is rounded to -2.0
N_2 = ceil(N/2);
%create a plot where the x axis has a log scale (semilogx)
%x axis is log Hz, ranging from 1:N2
subplot(5,5,d)
%y axis converts the values of X_mags to dB using 20*log10
semilogx(fax_Hz(1:N_2), 20*log10(X_mags(1:N_2)))
xlabel('Frequency (Hz)')
ylabel('Power (dB)');
axis tight
end 

[Adam Danz]

It looks like this is what you're trying to do

signal = grainsleft{d}{:,1};

• grainsleft is a cell array.
• grainsleft{d} is a table
• grainsleft{d}{:,1} is the first column of the table