I'm trying to generate a matrix such that:
Diagonal elements are 1
All other elements are 0.5
I'm trying to modify the example for the identity matrix:
{x=/:x}#til 4
to squeeze in my special function:
shrinkfn: {$[x=y;1;0.5]}
but I'm struggling. What's the best way to do this?
q)m:{x=/:x}#til 4
q)?'[m;1;0.5]
1 0.5 0.5 0.5
0.5 1 0.5 0.5
0.5 0.5 1 0.5
0.5 0.5 0.5 1
Alternative method:
https://code.kx.com/phrases/matrix/#identity-matrix-of-order-x
q)f:{(2#x)#1f,x#.5}
q)f 5
1 0.5 0.5 0.5 0.5
0.5 1 0.5 0.5 0.5
0.5 0.5 1 0.5 0.5
0.5 0.5 0.5 1 0.5
0.5 0.5 0.5 0.5 1
Explanation:
we can use the the following notation to create a matrix:
q)3 3#til 9
0 1 2
3 4 5
6 7 8
when the list runs out of elements it repeats:
q)3 2#til 4
0 1
2 3
0 1
with 5 by 5 matrix the the next diagonal is always 6 places, thus the list is of length 6:
q)5 5#1 .5 .5 .5 .5 .5
1 0.5 0.5 0.5 0.5
0.5 1 0.5 0.5 0.5
0.5 0.5 1 0.5 0.5
0.5 0.5 0.5 1 0.5
0.5 0.5 0.5 0.5 1
For the sake of variety another option is:
{0.5 1f x=/:x}til 4
This will use the boolean lists (0 or 1b) to index into our two element array and distribute the values accordingly along the matrix.
q){x=/:x}til 4
1000b
0100b
0010b
0001b
q){0.5 1f x=/:x}til 4
1 0.5 0.5 0.5
0.5 1 0.5 0.5
0.5 0.5 1 0.5
0.5 0.5 0.5 1
Related
I am trying to make a program in matlab to get this numbers:
0 1 0
0 0.8 0.2
0 0.6 0.4
0 0.4 0.6
0 0.2 0.8
0 0 1
0.1 0.9 0
0.1 0.7 0.2
0.1 0.5 0.4
0.1 0.3 0.6
0.1 0.1 0.8
0.1 0 0.9
and so on but I cant make the program to reduce the values of the second and third column when the first column increases. This is my code. Thanks
lai=0:0.1:1;
laj=1:-0.2:0;
lat=0:0.2:1;
for i=1,length(lai)
for j=1,i
for t=1,j
j
lam1(1,:)=lai;
lam2(1,:)=laj;
lam3(1,:)=lat;
end
end
end
Try this and do some thinking for what you require.
for i=0:0.1:0.1
for j=0:0.2:1
disp([i,j,1-j])
end
end
if i have text file that has three column say
1 2 1
3 1 1
2 3 1
and also have a matrix s =
[0.3 0.4 0.6
0.1 0.5 0.7
0.2 0.11 0.9]
firstly:
with respect to text file, i want to consider first column as i and second column as j then if the third column equal 1 then put its corresponding value in matrix s in new array say A else put remaining value in matrix s in new another array say B.
i.e i want this result
A=[0.4, 0.2, 0.7] B=[0.3, 0.6, 0.1, 0.5, 0.11, 0.9]
coordinates = [1 2 1
3 1 1
2 3 1];
s = [0.3 0.4 0.6
0.1 0.5 0.7
0.2 0.11 0.9];
linindices = sub2ind(size(s), coordinates(:, 1), coordinates(:, 2))';
A = s(linindices)
B = s(setdiff(1:numel(s), linindices))
I have a matrix proba (size :10 * 5).
proba=[0.5 0.3 0.8 0.9 0.8;
0.50 0.36 0.58 0.58 0.98;
0.1 0.25 0.6 0.8 0.9;
0.5 0.3 0.8 0.9 0.8;
0.2 0.9 0.58 0.58 0.69;
0.58 0.14 0.1 0.2 0.3;
0.25 0.9 0.8 0.7 0.5;
0.58 0.69 0.25 0.1 0.1;
0.1 0.25 0.36 0.2 0.3;
0.5 0.3 0.8 0.9 0.8 ];
I want to transform this matrix into a text file (proba.txt) with which the index column is written and the value of the column for each line as follows :
1 0.5 2 0.3 3 0.8 4 0.9 5 0.8
1 0.50 2 0.36 3 0.58 4 0.58 5 0.98
.
.
.
1 0.5 2 0.3 3 0.8 4 0.9 5 0.8
Please I need help, how can I do it?thanks in advance
You can use this function, it is useful for every matrix.
function data = addIndex(X)
[r, c] = size(X);
index = ones(r, 1);
data = zeros(r, 2 * c);
for i = 1:c
data(:, 2 * i - 1) = i .* index;
data(:, 2 * i) = X(:, i);
end
dlmwrite('proba.txt', data, '\t')
end
you can easily do this using dlmwrite, but first you want to add the column of indexes in front of your matrix:
function result = writematrix(proba)
rowind = 1:size(proba,2);
for t = 1:size(proba,1);
C(t,:,:) = [rowind',proba(t,:)']';
D(t,:) = C(t(:),:);
end
dlmwrite('filename.txt',D,'\t') %//I assume you want tab delimiter, if you want space, it is ' ' instead
%//dlmwrite('filename.txt',D,' ')
end
Note that this will write the text file into your local directory, and that it only works for numerical values, not strings, for strings, it is better to use csvwrite.
EDIT : Ops, didn't read the question fully, this should now work fine.
I don't see the bug anymore...maybe (very probably :-) ) there's even a much more easier and faster way of doing it...
I summarized the important columns of my huge data frame in a little expData (see below).
The problem is actually quite easy, but I'm just blind for the easy idea of solving it..
My objective is to reshape columns b,c,d into one column that expData afterwards looks like expData2.
I would be really happy, if someone could help me out.
My code so far:
a = [1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5]';
b = [0.3 0.3 0.3 0.3 0.3 0.4 0.4 0.4 0.4 0.4 0.5 0.5 0.5 0.5 0.5 0.8 0.8 0.8 0.8 0.8 0.9 0.9 0.9 0.9 0.9]';
c = [0.4 0.4 0.4 0.4 0.4 0.6 0.6 0.6 0.6 0.6 0.8 0.8 0.8 0.8 0.8 0.9 0.9 0.9 0.9 0.9 0.1 0.1 0.1 0.1 0.1]';
d = [0.5 0.5 0.5 0.5 0.5 0.1 0.1 0.1 0.1 0.1 0.7 0.7 0.7 0.7 0.7 0.2 0.2 0.2 0.2 0.2 0.3 0.3 0.3 0.3 0.3]';
e = rand(25,1);
f = rand(25,1);
a2 = [2 3 4 2 3 4 2 3 4 2 3 4 2 3 4]';
b2 = [0.3 0.4 0.5 0.4 0.6 0.1 0.5 0.8 0.7 0.8 0.9 0.2 0.9 0.1 0.3]';
c2 = rand(15,1);
d2 = rand(15,1);
expData = horzcat(a,b,c,d,e,f);
expData2 = horzcat(a2,b2,c2,d2); % for explanation of my objective
k = horzcat(expData(:,2),expData(:,3),expData(:,4))'; % How I wanted to do it
expData(:,2:4) = [];
k = reshape(k,[],1);
for index = 1:size(expData,1)
if expData(index,1) == 1
expData(index,:) = [];
end
if expData(index,1) == 5
expData(index,:) = [];
end
end
k = k(1:size(expData,1),:);
expData2 = [expData k];
Your current code throws an error, since the number of loop iterations gets determined at the beginning of the loop. As you are removing rows of expData, you run out of rows to index at some point.
The quick fix would be to start looping from the back, i.e. use for index = size(expData,1):-1:1. This way, you can safely remove rows without running into indexing problems.
The elegant fix is to use ismember to identify rows to remove:
rows2remove = ismember(expData(:,1),[1 5]);
expDate(rows2remove,:) = [];
I would like to only show these x-values on the x-axes
xx=[0.0005 0.005 0.05 0.1 0.25 0.5 0.75 1 1.25 1.5];
Is it possible?
You can modify axis labels using XtTickLabel property. For example:
set(gca,'XTickLabel',[0.0005 0.005 0.05 0.1 0.25 0.5 0.75 1 1.25 1.5])
This will change only labels, not actual values on the plot. To check values as well you can use:
set(gca,'XTick',[0.0005 0.005 0.05 0.1 0.25 0.5 0.75 1 1.25 1.5]);
set(gca,'XScale','log'); % Your xx values seem to be logarithmic, so this can help.