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plot with points in file

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Roger Nadal
Roger Nadal 2019년 12월 10일
댓글: dpb 2019년 12월 11일
i have text file and have to create a function that will read a file which contain x and y cordinates for the data points and which will create a stem plot using n points random.
  댓글 수: 8
Roger Nadal
Roger Nadal 2019년 12월 10일
I am reading file using fopen but on x axis the points I want is total number of points in the file and after passing suppose n=20 it should plot 20 random points but the x axis should not changed

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답변(2개)

dpb
dpb 2019년 12월 11일
편집: dpb 2019년 12월 11일
Well, still kinda' difficult to figure out exactly what is wanted, but as near as I can make out, something like;
t=readtable('file.txt'); % read the file
t=t(:,[2 4]); % get rid of the two x,y character columns
t.Properties.VariableNames={'x','y'}; % name two columns appropriately
% preliminaries out of way, the engine
nr=size(t,1); % rows in dataset
n=20; % arbitrary number points to plot initially and to choose randomly
ix=sort([1:n randperm(nr-n,n)+n]); % build the indexing vector of first n and n random thereafter
figure
stem(t.x(ix),t.y(ix)) % and stem() plot those...
QED
  댓글 수: 20
dpb
dpb 2019년 12월 11일
My understanding is he's actually wanting |xlim([0 x(end)]) regardless, so that's what I recommended above earlier.
But, expectations are so nebulous and getting information like pulling hens' teeth so I just said "salt to taste" this time...
Reminds of a DOE manager I worked for as consultant lo! those many years ago. I characterized working for him as being instructed "Bring me a rock!" When the rock was delivered, it was always "No, not that rock!" but could never say just which variety/size/shape/color of rock was desired until, finally, he either ran out of budget or (usually) would after third or fourth iteration suddenly decide the first or second was actually the one he was looking for after all... :)

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Bandar
Bandar 2019년 12월 11일
Assume data stored in this form
1 23
2 34
3 54
The code is
file = load('data.txt');
n=3;
x=file(randi(10,1,n),1); % 10:max 1:min n: points number
y=file(x,2);
stem(x,y)

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