how to import file?

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prabhu singh
prabhu singh on 12 Nov 2023
Answered: Voss on 16 Nov 2023
How to import all these csv files and extract only the 3 column from all these files and plot 3 column with respect to 2nd column data
T = readtable('3ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
a=T(:,3);
T1 = readtable('3.1ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
b=T1(:,3);
T2 = readtable('3.2ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
c=T2(:,3);
T3 = readtable('3.3ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
d=T3(:,3);
T4 = readtable('3.4ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
d=T4(:,3);
xaxis=120:0.1:120.5;
Final_T=cat(a,b,c,d);%i have to collect 3rd column data from all the files and store in 1 variable
Error using tabular/cat
Dimension must be 1 or 2 for a 2-D table.
plot(xaxis,Final_T)

Answers (2)

Les Beckham
Les Beckham on 16 Nov 2023
You were pretty close. Here is one approach, converting your third columns to arrays instead of extracting them as tables with only one column.
Adjust as desired.
T = readtable('3ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
a = table2array(T(:,3));
T1 = readtable('3.1ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
b = table2array(T1(:,3));
T2 = readtable('3.2ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
c = table2array(T2(:,3));
T3 = readtable('3.3ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
d = table2array(T3(:,3));
T4 = readtable('3.4ghs_datafiles.csv','NumHeaderLines',3);%i have to eliminate 1 rows which is having header names a,b, r
e = table2array(T4(:,3)); % <<< don't overwrite d
% xaxis=120:0.1:120.5;
whos
Name Size Bytes Class Attributes T 22x3 1943 table T1 22x3 1943 table T2 22x3 1943 table T3 22x3 1943 table T4 23x3 1967 table a 22x1 176 double ans 1x43 86 char b 22x1 176 double c 22x1 176 double cmdout 1x33 66 char d 22x1 176 double e 23x1 184 double
% Final_T=cat(a,b,c,d);%i have to collect 3rd column data from all the files and store in 1 variable
xaxis = linspace(120, 120.5, numel(a)); % xaxis with the same number of elements as your other variables
e = e(1:22,:); % trim off the extra row from e
Final_T = [a b c d/1e64 e/1000]; % scale d and e so you can see that a, b, and c aren't all zeros
plot(xaxis, Final_T)
legend({'a', 'b', 'c', 'd/1e64', 'e/1000'}, 'Location', 'northwest')
grid on

Voss
Voss on 16 Nov 2023
Here's one way:
f = [3, 3.1, 3.2, 3.3, 3.4];
Nf = numel(f);
C = cell(1,Nf);
filenames = compose('%gghs_datafiles.csv',f);
for ii = 1:Nf
C{ii} = readtable(filenames{ii});
end
T = vertcat(C{:});
plot(T.b,T.r,'.')
At least one of the files has huge values (~1e64) that prevent you from seeing what the other files' data looks like, so let me plot each file's data in a separate figure:
for ii = 1:Nf
figure
plot(C{ii}.b,C{ii}.r,'.')
title(filenames{ii},'Interpreter','none')
end

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