how can I read and draw a plot and histogram from txt file on Matlab.

Question

Yaren Duygu Atalay 2024-2-21

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编辑： Hassaan 2024-2-21

Hallo, I have a problem with reading txt file.my data is in notepad it is a table basicly which seperate the data with ; sign. I want to read and draw a histogram with this data but there is an error by read or scan commands. My question is how can I read and draw a plot and histogram from this file on Matlab.

the table looks;

STATIONS_ID;MESS_DATUM; QN;FF_10;DD_10;eor

11;202307260800; 3; -999;-999;eor

11;202307260810; 3; -999;-999;eor

11;202307260820; 3; -999;-999;eor

11;202307260830; 3; -999;-999;eor

11;202307260840; 3; 2.1; 200;eor

11;202307260850; 3; 2.5; 200;eor

11;202307260900; 3; 2.8; 250;eor

11;202307260910; 3; 3.8; 260;eor

11;202307260920; 3; 4.5; 280;eor

11;202307260930; 3; 5.5; 240;eor

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Aquatris 2024-2-21

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Would be benefical to add a sample txt file so someone can provide you the exact code. What kind of error are you getting? Did you try the built in 'import data' option which can also generate a script for you?

Example script generated by matlab for your example:

%% Setup the Import Options and import the data
opts = delimitedTextImportOptions("NumVariables", 6);
% Specify range and delimiter
opts.DataLines = [2, Inf]; % 1 is the name of the column, VariableNames
opts.Delimiter = ";";
% Specify column names and types
opts.VariableNames = ["STATIONS_ID", "MESS_DATUM", "QN", "FF_10", "DD_10", "eor"];
opts.VariableTypes = ["double", "double", "double", "double", "double", "categorical"];
% Specify file level properties
opts.ExtraColumnsRule = "ignore";
opts.EmptyLineRule = "read";
% Specify variable properties
opts = setvaropts(opts, "eor", "EmptyFieldRule", "auto");
% Import the data
tbl = readtable("C:\New Text Document.txt", opts);
%% Convert to output type
STATIONS_ID = tbl.STATIONS_ID;
MESS_DATUM = tbl.MESS_DATUM;
QN = tbl.QN;
FF_10 = tbl.FF_10;
DD_10 = tbl.DD_10;
eor = tbl.eor;

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Answer 1

Chunru 2024-2-21

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testdata.txt

a = readtable("testdata.txt");

a.MESS_DATUM = string(a.MESS_DATUM)

a = 10x6 table

STATIONS_ID MESS_DATUM QN FF_10 DD_10 eor ___________ ______________ __ _____ _____ _______ 11 "202307260800" 3 -999 -999 {'eor'} 11 "202307260810" 3 -999 -999 {'eor'} 11 "202307260820" 3 -999 -999 {'eor'} 11 "202307260830" 3 -999 -999 {'eor'} 11 "202307260840" 3 2.1 200 {'eor'} 11 "202307260850" 3 2.5 200 {'eor'} 11 "202307260900" 3 2.8 250 {'eor'} 11 "202307260910" 3 3.8 260 {'eor'} 11 "202307260920" 3 4.5 280 {'eor'} 11 "202307260930" 3 5.5 240 {'eor'}

histogram(a.DD_10, 5) % 5bins

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Answer 2

Hassaan 2024-2-21

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编辑：Hassaan 2024-2-21

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@Yaren Duygu Atalay An intial attempt to the problem:

% Define the path to your data file
filePath = 'Test.txt'; % Ensure this path is correctly set
% Import the data
opts = delimitedTextImportOptions('Delimiter',';', ...
                                  'VariableNamesLine', 1, ...
                                  'DataLines', 2);
data = readtable(filePath, opts);
% Convert FF_10 to numeric if it's not already, handling possible conversion issues
if iscell(data.FF_10)
    data.FF_10 = str2double(data.FF_10);
elseif ischar(data.FF_10)
    data.FF_10 = str2double(cellstr(data.FF_10));
end
% Filter out rows with -999 in FF_10
data = data(data.FF_10 ~= -999, :);
% Plot histogram
figure;
histogram(data.FF_10);
title('Histogram of FF_10 Values');
xlabel('FF_10');
ylabel('Frequency');

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