How to select specific rows with a certain range/certain value in another row?

25 次查看（过去 30 天）
Pinga
Pinga 2014-8-7
编辑： Pinga 2014-8-11
Two simple questions I haven't managed to find the right answers for:
1: I have a 1x1 cell called "Data". This 1x1 cell contains a 1x100 cell, so basically the 100th data would be Data{1,1}{1,100}. In the analysis I only want to include the data until cell 90. I've tried it with
Data = Data{1,1}{1,1:90}
which doesn't seem to work.
2: I have a 10x8 double. What I'd like to calculate is the mean value of all the values in row 2 for all data which value in their row 4 is "5".
Any help would be appreciated.

请先登录，再回答此问题。

采纳的回答

Christopher Berry
Christopher Berry 2014-8-11
Pinga,
1. To get Data as a 1x90 cell array, use the following code:
Data = Data{1}(1:90)
There are two ways to refer to the elements of a cell array. Enclose indices in smooth parentheses, (), to refer to sets of cells—for example, to define a subset of the array. Enclose indices in curly braces, {}, to refer to the text, numbers, or other data within individual cells.
2. Assume that your 10x8 double data is in A
mean(A(2,A(4,:)==5));
Here, A(4,:)==5 returns a logical vector of each column containing a '5' in row 4, which you then use to logically index into row 2 columns.
Hope that helps.
  3 个评论
显示 1更早的评论
Christopher Berry
Christopher Berry 2014-8-11
Ok, I think I understand what you are asking, but if I get it wrong let me know.
1. What you want sounds like
Data = {Data{1,1}(1:90)}
This way your size of data is 1x1 cell, whose 1st cell contents are a 1x90 cell array.
2. When you say "I meant columns, not rows", I am going to guess your question should have been "What I'd like to calculate is the mean value of all the values in column 2 for all data which value in their corresponding row column 4 is "5".
And it looks like that is what you are doing, but with misplaced (). Try this instead
mean(A(A(:,4)==5,2))
Notice the lack of ) after "5" and the double )) at the end of the line.
Pinga
Pinga 2014-8-11
编辑：Pinga 2014-8-11
Super, that was a really great help - thanks a lot! Although having worked with Matlab for a few months now, it appears to me, I'm just adapting way too slowly on this whole new programming stuff (such misplaced () keep me troubleshooting and frustrating quite some time).

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Loops and Conditional Statements 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by