How to set an upper and lower limit on a data set from a matrix

Question

jgillis16 2015-8-3

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/232222-how-to-set-an-upper-and-lower-limit-on-a-data-set-from-a-matrix

评论： jgillis16 2015-8-4

采纳的回答： Walter Roberson

I need to set an upper and lower limit on the numbers in a data set that belongs to a matrix.

How would I go about doing this?

2 个评论
显示无隐藏无

James Tursa 2015-8-3

Please provide a short example showing inputs and desired output.

jgillis16 2015-8-3

I have a data set that goes from 0 to 360 that is apart of a matrix called GalList >>> GalList(:,3). I need to extract values ranging only from 176.71 to 198.71.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2015-8-3

4
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/232222-how-to-set-an-upper-and-lower-limit-on-a-data-set-from-a-matrix#answer_188126

在 MATLAB Online 中打开

at_least = -5.1234;   %for example
at_most = 308.42;     %for example
new_matrix = min(max(YourMatrix, at_least), at_most);

Now new_matrix has had every value less than at_least replaced with at_least, and every value greater than at_most replaced with at_most.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

Answer 2

James Tursa 2015-8-4

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/232222-how-to-set-an-upper-and-lower-limit-on-a-data-set-from-a-matrix#answer_188130

在 MATLAB Online 中打开

Assuming you want to extract all the rows where the 3rd column meets your conditions:

GalList = your matrix
lower_limit = 176.71;
upper_limit = 198.71;
x = (GalList(:,3) >= lower_limit) & (GalList(:,3) <= upper_limit);
extracted_rows = GalList(x,:);

3 个评论
显示 1更早的评论隐藏 1更早的评论

James Tursa 2015-8-4

Do you mean read in only those lines, or create a new file with only those lines, or what? How are you currently reading this file?

jgillis16 2015-8-4

在 MATLAB Online 中打开

Currently, my code looks like the following:

load virgoclusterrm.txt %loads text into workspace
readCatalog( virgoclusterrm )
fid = fopen( 'virgoclusterrm.txt');
trashLine = fgets(fid); %Skips the first line
data = textscan(fid, '%f%s%f%f%s%f%f%f%f%f%f%f%f%f%f%f%f%f', 'Delimiter', '|', 'TreatAsEmpty','~');
fclose(fid);
GalList.pgc = data{1};
GalList.name = data{2};
GalList.ra = data{3};
RA = GalList.ra.*15;
GalList.dec = data{4};
GalList.major = data{7};
GalList.abs_mag = data{14};
GalList.dist = data{15};
lower_limit = 176.71;
upper_limit = 198.71;
x = (RA >= lower_limit) & (RA <= upper_limit);
extracted_rows = RA(x,:);
RAo = extracted_rows./15;

RAo contains the values I restricted column 3 to. But, column 3 was originally derived from the text file, virgoclusterrm.txt. Now, I have these 877 values but I want to correlate them back to their respective lines of text.

Would there be any way to scan the original text file for the values in RAo in column three, and extract any matches into a new text file?

请先登录，再进行评论。