How do I subplot from a large file? Note..any .txt file of any large figures can be given. So please solve generally.

I have to plot time against distance. But any .txt file will be given which may contain any number of datas. How do I subplot them in a loop?

[Walter Roberson]

Will the text file contains a header for each group? If not then how to tell where each group ends?

[anonymous]

No header. I will just read the data and plot it in matlab. All the data must be plotted as many amount is given in the text file. So I need to use a loop. I've seen other examples I didn't understant. https://au.mathworks.com/matlabcentral/answers/467078-how-to-generate-the-n-number-of-figure-for-n-numbers-of-subplots here it is. Can you solve this specific problem?

[Jan]

It is not clear, what your problem is. You mention "subplot", but I do not see a reason for subplots, if all you want is to draw one diagram, even if the file is "large". By the way, "large" might mean TeraByte. Then plotting in a diagram is not useful, because neither the monitor can display this number of pixels, nor does the human brain understand this pile of information.

"All the data must be plotted as many amount is given in the text file. So I need to use a loop." - I do not understand this. Why do you assume that a loop is needed?

[Rik]

Why don't you show the figure you want to end up with for this data? Then it will be easier for us to help you.

[anonymous]

code should be like this, but I don't know where my mistake is.

[Rik]

It is good that you showed the code you tried, however, without a better description (even with MS Paint) of the intended result, it is hard to help you. Also, you should post your code as code, instead of a screenshot.

Answer 1

[Walter Roberson]

You could calculate N more cleanly as

N = size(r, 1);

T and c and r will each be a single column.

You take the number of rows in r, and take the square root of it, and want to do subplots; if everything works out and the number of input rows was a square integer, you would end up with a number of subplots equal to the number of rows.

In each iteration, you go to plot one column . But r and c only have one column, so the second iteration would produce an error.

You should not be calculating

cols = ceil(n./rows)

Suppose for example there were 50 rows to start, so N = 50, so rows = floor(sqrt(50)) so rows = 7. Then n = [50 1] (because size(r(:,end)) is going to be a vector of length 2, the second element of which is 1). [50 1]./7 is [7.14<etc>, 0.14<etc>]. ceil([7.14<etc>, 0.14<etc>]) is [8 1]. But using [8 1] as a subplot bound is an error. You should be using cols = ceil(N./rows)

Now you go to iterate i = 1 : N and you go to plot() one column each time. But there is only one column... You could switch to using i as the row index, but if you did that you would be plotting only one point per subplot.