I need a little help with tables.

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Tamás Zsombor Tolvaj
编辑： Sayan 2023-11-22
The task wants a table in return, where:
-the first column shows the time,
-the second column shows numbers (from -5 to 5),
-the third column shows the grades (they are strings) determined by rounding the numbers in the second column
-and the columns are named: ido, eredmeny and ertekeles.
This is the code Ive found on one of the older sites with the same task, but it doesnt work.
function tbl = f91()
t = 0:0.001:pi;
for i=1:length(t)
switch round(abs(5*sin(3*exp(t(i)))))
case 1
et{i, 1} = 'elegtelen'
case 2
et{i, 1} = 'elegséges'
case 3
et{i, 1} = 'kozepes'
case 4
et{i, 1} = 'jo'
case 5
et{i, 1} = 'jeles'
otherwise
et{i, 1} = 'elegtelen'
end
end
tbl = table(t', 5*sin(3*exp(t')), et, 'VariableNames', {'ido', 'eredmeny', 'ertekeles'});
end
  2 个评论
Dyuman Joshi
Dyuman Joshi 2022-5-7
Ran in:
It is working.
If the output is not what it is expected to be, mentioned that explicitly.
Use round while defining your table, round(5*sin(3*exp(t')))
t = 0:0.001:pi;
for i=1:length(t)
switch round(abs(5*sin(3*exp(t(i)))))
case 1
et{i, 1} = 'elegtelen';
case 2
et{i, 1} = 'elegséges';
case 3
et{i, 1} = 'kozepes';
case 4
et{i, 1} = 'jo';
case 5
et{i, 1} = 'jeles';
otherwise
et{i, 1} = 'elegtelen';
end
end
tbl = table(t', 5*sin(3*exp(t')), et, 'VariableNames', {'ido', 'eredmeny', 'ertekeles'})
tbl = 3142×3 table
ido eredmeny ertekeles _____ ________ _____________ 0 0.7056 {'elegtelen'} 0.001 0.69074 {'elegtelen'} 0.002 0.67586 {'elegtelen'} 0.003 0.66096 {'elegtelen'} 0.004 0.64603 {'elegtelen'} 0.005 0.63109 {'elegtelen'} 0.006 0.61612 {'elegtelen'} 0.007 0.60114 {'elegtelen'} 0.008 0.58613 {'elegtelen'} 0.009 0.5711 {'elegtelen'} 0.01 0.55606 {'elegtelen'} 0.011 0.54099 {'elegtelen'} 0.012 0.5259 {'elegtelen'} 0.013 0.5108 {'elegtelen'} 0.014 0.49567 {'elegtelen'} 0.015 0.48052 {'elegtelen'}

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回答（2 个）

Sayan
Sayan 2023-9-25
编辑：Sayan 2023-11-22
Hi Tamás Zsombor Tolvaj,
I understand from your issue that column 2 of your table with the name "eredmeny" should be within the desired value, i.e., -5 to 5 in the table.It is showing the same in your code too.
However, you can follow the below code snippet as an alternative to find the same.
%you can randomly generate the uniformly distributed values
%for t in the range of (-pi/2 to pi/2)
t=-pi/2+rand(1,N)*pi %Here N data points are taken,you can change the value as per requirement
%run the other part of the code as mentioned in the question
%Change the values of second column using this new equation to find the
%range of -5 to 5
tbl.eredmeny=(5*sin(t))';
You can further find more information on "table" and "rand" function in the following MATLAB documentation
Hope this helps you in resolving the issue.
Image Analyst
Image Analyst 2023-9-25
编辑：Image Analyst 2023-9-25
Ran in:
Like some of the others said, the code is working in that it does give numbers in column 2 in between -5 and 5 (if that's what you meant by "not working"). However it can be improved in several ways, and I do that here:
% Initialization steps.
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
tic
tbl = f91();
toc
Elapsed time is 0.035508 seconds.
% Find range of the sin formula in column 2
plot(tbl.eredmeny, 'b-')
title('tbl.eredmeny', 'FontSize',fontSize);
grid on;
yline(0, 'LineWidth',3); % Draw a y axis.
% Print out the max and min
fprintf('Max Value = %f, min value = %f.\nNumber of rows in table = %d\n', max(tbl.eredmeny), min(tbl.eredmeny), height(tbl));
Max Value = 4.999996, min value = -5.000000. Number of rows in table = 3142
%----------------------------------------------------------------------------------------------------------
function tbl = f91()
t = linspace(0, pi, 3142);
numRows = numel(t);
eredmeny = 5 * sin(3 * exp(t(:)));
et = cell(numRows, 1);
for k = 1 : numRows
switch round(abs(eredmeny(k)))
case 1
et{k} = 'elegtelen';
case 2
et{k} = 'elegséges';
case 3
et{k} = 'kozepes';
case 4
et{k} = 'jo';
case 5
et{k} = 'jeles';
otherwise
et{k} = 'elegtelen';
end
end
tbl = table(t(:), eredmeny, et, 'VariableNames', {'ido', 'eredmeny', 'ertekeles'});
end
However if by "not working" you meant something else, say what it is. Did you call the function from a script, or did you just click the green run triangle?
Perhaps the numbers from -5 to 5 should be generated by rand rather than that trig function you used.
eredmeny = -5 * 10 * rand(numRows, 1);
Did your task say specifically to use that, or was it just there from that other code you copied?

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