Error in splitapply command

I am using this command "splitapply" in order to find mean (average) of a group of data.

edges=1:0.5:10
[N, edges, bin] = histcounts(B, edges);
mean_B=splitapply(@mean, B, bin) %mean
%B is 1000x1 double 

But command window shows me :

Error using splitapply (line 61)

Group numbers must be a vector of positive integers, and cannot be a sparse vector.

which is curiousness because for an another set of data code runs.

Could you please help me?

Answer 1

[Image Analyst]

This seems to work fine:

B = 1 + 9 * rand(1, 100000);
edges = 1 : 0.5 : 10
[counts, edges, bin] = histcounts(B, edges);
% bin says what bin the value was placed into.
% Compute the means of the values in each bin.
mean_B = splitapply(@mean, B, bin) 

Attach your B so we can see why it's different than mine. If your B exceeds 10, it will say that bin is zero for those values exceeding 10, and that would be a problem since you're passing in bin as the "group number" and the group numbers have to be natural numbers (1,2,3,4,...) and not zero.

[Ivan Mich]

Ok , my full code is:

edges=1:0.5:10

[N, edges, bin] = histcounts(B, edges);
 Result          = accumarray(bin, A);

Y = discretize(B,edges)
% Y=rmmissing(Y)

mean_IMM=splitapply(@mean, A, bin) %mean

I am attaching the data.txt file (A id first column, B is second column).

I would appreciate if you could help me

[Walter Roberson]

2  0.73834617

Your bins start at 1 but you have data less than 1 which would be getting a bin number of 0

[Ivan Mich]

Ok. If I want to throw out values <1 of B column and simultaneusly the corresponding values of column A how could I make it?

[Ivan Mich]

Also I have one problem. I have change edges=0:0.5:10, but command window shows me:

Error using splitapply (line 111)

For N groups, every integer between 1 and N must occur at least once in the vector of

group numbers.

How could I fix it?

I am attaching file

[Image Analyst]

That's not the full code. For example there is no code to read in 'data.txt' and derive B from it. And you seem to have two input files: a text file and a workbook. Which is it? In general to get rid of values less than 1 you can do

badNumberMask = data < 1;
B = data(badNumberMask);

[Ivan Mich]

This is the rest code

filename1= 'data.txt' 

[d1,tex]= importdata(filename1);

A=d1.data(:,1);

%B is a result from an equation including A values.

[Image Analyst]

The last line got cut off. We're not seeing how B is computed from A. Come on, make it EASY for us to help you, not hard. And did you try my code to remove numbers less than 1?

[Ivan Mich]

%the equation is 
B=4*A -0.3

Yes I tried it but it is no use...

[Image Analyst]

Ivan:

Just give me the whole script. Attach it with the paper clip icon. Because the following code, with the data.txt you attached (and I'm attaching again here) doesn't work. It doesn't give me A or B.

fileName1 = 'data.txt';
[d1, tex] = importdata(fileName1)

A = d1.data(:,1);
% B is a result from an equation including A values.
% the equation is 
B = 4 * A - 0.3

edges = 1 : 0.5 : 10
[counts, edges, bin] = histcounts(B, edges);
% bin says what bin the value was placed into.
% Compute the means of the values in each bin.
mean_B = splitapply(@mean, B, bin) 

I'm very close to giving up on this, but giving you another chance to make it right. I'm sure over the past 3 hours you have new code by now so attach that. I don't have much time today to go back and forth on this just to get to a starting point.

Dot indexing is not supported for variables of this type.

Error in test7 (line 4)

A = d1.data(:,1);

[Walter Roberson]

Your first column has values up to 10. 4*10-0.3 is 39.7 and 39.7 is outside the range 1:0.5:10 so values anywhere near that large would get assigned bin 0.

Your second column has values up to about 7.5. 4*7.5-0.3 is about 29.7 and 29.7 is outside the range 1:0.5:10 so values anywhere near that large would get assigned 0.

Your first column has values from 2 to 10, and that would fit in 1:0.5:10 if you used it directly.

Your second column has values from 0.73834617 to about 7.5, but 0.738 is before 1:0.5:10 so those small values would be assigned bin 0 if you were to bin your second column directly.

[Ivan Mich]

Thank you, nut my question still exist. How can I throw out /reject some data.

For example, if I want to throw out values <1 of B column and the corresponding to them A values which command should I use?

[Walter Roberson]

mask = B < 1;
newA = A(mask) ;
newB = B(mask);

[Image Analyst]

Keep in mind that you can't delete/remove elements from a array with more than 2 dimensions because it must remain rectangular. It can't have "holes" or "ragged edges" in it. You can only remove elements from a 1-D vector.

If you have a 2-D matrix and get a map of where it's above or below some threshold, then if you pass that into the 2-D matrix as a logical index, it can't give you a 2-D matrix back with "holes" in it where the non-selected elements are missing. So it returns the elements all concatenated in a 1-D vector pulled from the original matrix in a "column major" manner.