Plot muliple data files into one plot

Hi, I've spent about 3 days trying to figure out how to plot muliple data files into 1 plot. I know it is possible as I have done it before. Basically I have 10 csv files of monthly data I want to plot. Below is a screen shot of how I can plot one but I cannot figure out how to combine the data to be able to plot the whole year.

I have also a

Also here is my script on how I have worked with the data I have got:

Function script:

function data=processfile(filename)

function data=processfile(filename)

% function to load data from COPEPOD
% input is the filename of the data file
% output is the Year/Month and Adundance from the data file
% tmp=tempory l=line

data.filename=filename; %each time i look at output data with contain name of data file it loaded data from 

fid=fopen(filename); %opens up data file

%Skips headerlines
for I=1:18 %loop to repeat until the desired line is reached e.g. 18 is when the text that i am interested in starts 
    tmpl=fgetl(fid); %fgetl=function get line %fid=file identifier %tmpl=asssigned name of variable to capture each line 
end

disp(tmpl)

J=1;
while ischar(tmpl)
%     21 strings
    tmp=textscan(tmpl,'%s',32,'Delimiter',','); %takes the input of the loop line with format spec= what we are going to break it into e.g. %s = strings
    tmp{1}(2)
    data.date(J)=datenum( str2num( cell2mat(tmp{1}(2))), str2num( cell2mat(tmp{1}(3))),str2num( cell2mat(tmp{1}(4))))+str2num( cell2mat(tmp{1}(5)))/24; %year, month, day, time /fraction of day adding onto date
    
    %data.P=str2num(cell2mat(tmp{1}(22))); %plankton amount %datestr(data1994_april.d) to display date properly
    tmpPlankton=str2num(cell2mat(tmp{1}(22)));
    if isempty(tmpPlankton)
        tmpPlankton=NaN
    end
    data.Plankton(J)=tmpPlankton;
    
    tmpl=fgetl(fid);
    J=J+1;
end

Plotting script:

function plotdata(data)

% function to plot the Giovanni SST data imported with load_giovanni_data

figure(1)
clf
plot(data.date,data.Plankton,'.b-','MarkerEdgeColor','r','MarkerSize',17,'LineWidth', 1.5)
datetick('x')
ylabel('Plankton', 'fontsize', 16)
xlabel('Date', 'fontsize', 16)
%title('-4.9438,50.647,-4.7351,50.9436,  2002-2012 SST', 'fontsize', 14)

I will literally marry anyone who is able to figure this out. Thanks everyone

[dpb]

The key element to add additonal data to an existing axis is to call hold on before subsequent calls to plot() after the first. Otherwise, it simply begins a fresh plot each time.

Your code looks to be quite inefficient in handling lots of cell arrays that probably aren't needed but without one or two of the data files to see just what really have not much else we can do just looking at screen shots.

Code w/o data isn't of much help--better than no code because I didn't see the key missing element anywhere, but a complete working demo of the problem would be bestest...