Using sscanf function in a for loop.

Question

Mark Coughlin 2020-4-18

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/518899-using-sscanf-function-in-a-for-loop

回答： Ameer Hamza 2020-4-18

Write a script which will use the function uigetfile to read in the name of a file to open in the script. The function fopen is used to open the file, the contents of this file is shown below. The function fgetlis used to read in a line, as can be seen below; this line will contain the character 7. The function sscanfshould be used to convert this to an integer. This will be used to form a for loop which will read in the rest of the lines. The contents of these lines will be converted to the points of the sine curve using sscanf. The function should then plot the data contained in the file as a 2-D line plot.

The file contains the data:

7

0 0.000

15 0.2588

30 0.5000

45 0.7071

60 0.8660

75 0.9659

90 1.0000

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Ameer Hamza 2020-4-18

The statement of this question makes me think it is a task for a homework. What have you already tried?

Mark Coughlin 2020-4-18

在 MATLAB Online 中打开

Hi Ameer,

This is a practice question in a previous exam paper for which I will not get the solution for. I have tried the following:

[filename,pathname]=uigetfile('*.txt');
if filename==0
    return
end
fileID=fopen([pathname,filename]);
textline=fgetl(fileID);
n=sscanf(textline,'%f',[1 1]);
linecount=1;
for i=1:n
    textline=fgetl(fileID);
    [output]=sscanf(textline,'%f %f',[1 2]);
end
x(i,1)=output(1);
sinx(i,2)=output(2);
xmin=min(x);
xmax=max(x);
plot(x,sinx);
xlabel('x');
ylabel('sinx');
title('Sine Curve');
xlim([xmin xmax]);
fclose(fileID);

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Answer 1

Ameer Hamza 2020-4-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/518899-using-sscanf-function-in-a-for-loop#answer_426793

在 MATLAB Online 中打开

Compare it with your code to find the differences.

[filename,pathname]=uigetfile('*.txt');
if filename==0
    return
end
fileID=fopen([pathname,filename]);
textline=fgetl(fileID);
n=sscanf(textline,'%f',[1 1]);
linecount=1;
output = zeros(n,2);
for i=1:n
    textline=fgetl(fileID);
    output(i,:)=sscanf(textline,'%f %f',[1 2]);
end
x=output(:,1);
sinx=output(:,2);
xmin=min(x);
xmax=max(x);
plot(x,sinx);
xlabel('x');
ylabel('sinx');
title('Sine Curve');
xlim([xmin xmax]);
fclose(fileID);