Grouping imported data and exporting into a .txt file

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Jia Qing Soo
Jia Qing Soo 2013-10-3
评论： Cedric 2013-10-3
I am suppose to import the following data from a .txt and then sort them accordingly. Those in bold are the variables, depending on the imported data. The sorting is done (>=80) - distinction, (>=50, <=79) - pass, (<=49) - file.
*56
88
32
16
99
78
44
63*
-----------------------------------------------------------------
The sample output to a .txt file is,
2 students scored a distinction. Their scores are
*88
99*
3 students scored a pass. Their scores are
*56
78
63*
3 students scored a fail. Their scores are
*32
16
44*
  2 个评论
Cedric
Cedric 2013-10-3
And what have you done or tried by yourself so far?
Jia Qing Soo
Jia Qing Soo 2013-10-3
Thus far i have,
clear;clc;
fid = fopen('Input.txt');
a = fscanf(fid,'%g',inf);
fclose(fid);
len = length(a);
fid2 = fopen('Output.txt','wt');
I was thinking of using "if,else" but have no idea how to continue the code.

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Cedric
Cedric 2013-10-3
编辑：Cedric 2013-10-3
Ok, the code that you provided in your comment is a good start. Here is a hint: define
>> x = [9, 3, 6, 7, 1, 2] ;
Then, for example
>> cond = x > 5
cond =
1 0 1 1 0 0
is a vector of logicals whose elements indicate where the condition is true (1) or false (0) for each element of x. A remarkable property of these vectors of logicals is that you can use them for indexing the original vector x, i.e. for getting all elements which satisfy the condition:
>> y = x(cond)
y =
9 6 7
Now you can work with y, e.g. compute its length, output it to file, etc..
Once you'll understand that, you'll have all you need to go on with this homework I guess.
  2 个评论
Jia Qing Soo
Jia Qing Soo 2013-10-3
编辑：Jia Qing Soo 2013-10-3
However, i am still having problem with the fprintf portion.
cond = a>= 80
y = a(cond)
fprintf('%g students scored a distinction. Their scores are\n%g',___,y)
The "___" is the portion i have no idea what to type. How do i calculate the length of variables that has >= 80? And my "y" has 2 numbers, so how do i display both numbers?
Expected output is,
2 students scored a distinction. Their scores are
*88
99*
Cedric
Cedric 2013-10-3
For the first question:
doc length
For the second question, you cannot output an array with only one %g at the end of this formatSpec string that you are using. You have essentially two options: the first is a FOR loop over elements of vector y, which prints '%g\n' for each element. The second is a print using the same format '%g\n' directly on the y array, and use the fact that FPRINTF repeats the format as long as it "finds elements to output in the array".
I cannot say much more without giving you the answer directly. The best thing that you can do is to experiment with a small y array that you build by hand, and see whether you can understand what I said about repeated format, or try to implement a FOR loop.

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