Inserting data of one matrix into another
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If I have a vector a
0
0
1
1
0
0
and a vector b
5
6
and I want to input the data of b into the nonzero elements of a (which will always be together and matching the dimensions of b), so that vector c reads
0
0
5
6
0
0
What is an easy way to do this? Thank you!
Another example that it needs to work for:
a b c
_ _ _
0 4 0
0 8 0
1 3 ----> 4
1 7 8
1 3
1 7
采纳的回答
a(a ~= 0) = b
10 个评论
Chris
2014-9-26
Adam
2014-9-26
It works fine when I try it! And also for your other example. Are you sure you typed it exactly the same way?
José-Luis
2014-9-26
No, it shouldn't, given the provided data. Please post the code you are using.
Star Strider
2014-9-26
Interesting. It works for me, replacing the appropriate elements of ‘a’ with the elements of ‘b’.
Ah well, your vector is logicals, not doubles! That makes it more, well...logical...in terms of syntax!
Since you don't care if it is in the same vector or a different vector then
c(a) = b;
c = c';
should work, inserting your own variable names as appropriate. There's probably a slightly neater way of getting back to a vertical vector. You can pre-allocate c as:
c = zeros(size(a));
if you prefer or if you don't care whether your result is a row vector or a column vector you can leave off the c' line. I don't generally like code myself though that switches between column and row vectors mid-way through a calculation.
This should work:
d = [-0.8; -0.001];
U = [0 0 1 1 0 0]';
U(U~=0) = d
If it doesn't, then d and U (or both) probably don't contain what you think they do. Also, the common lingo for "vertical vector" is "column vector".
José-Luis
2014-9-26
Please accept the answer of it solved your problem.
Shane Hagen
2015-4-3
I have a slightly different issue maybe someone can help?
I have a matrix [signal] of 315954x64 of signal data. In another matrix [FFlash] (155520x1) there is logical 1 or 0 depending on an activation
I have categorized the signal matrix to obtain a matrix [FFsignal] (155520x64) of data when there is an activation
To graph I need matrices of similar dimensions so I wanted to insert the categorized data into a matrix of zeros of size (315954x64)
For example the first group of activation is in rows 631-654 and when categorized I have data for those time points. I want to add this data to a matrix of zeros in the same time points if possible. Therego, zeros until 631-654 and so on through the set. Please help!
更多回答（2 个）
>> a = [false;false;true;true;false;false];
>> b = [5;6];
>> c = zeros(size(a));
>> c(a) = b
c =
0
0
5
6
0
0
And the same for the second example:
>> a = [false;false;true;true;true;true];
>> b = [4;8;3;7];
>> c = zeros(size(a));
>> c(a) = b
c =
0
0
4
8
3
7
3 个评论
Shane Hagen
2015-4-3
any insight on my issue stephen? I would really appreciate any help.
Shane Hagen
2015-4-3
I posted the question :Inserting data into matrix of zeros from another matrix.
try simple
a=[0;0;1;1;0;0];
b=[5;6];
p=find(a>0);
a(p)=b
a =
0
0
5
6
0
05 个评论
James Tursa
2015-4-3
You have totally missed the issue. The 1's & 0's vector "a" is logical. So your scheme doesn't work. E.g.,
>> a = logical([0 0 1 1 0 0]);
>> b = [5 6];
>> p = find(a>0);
>> a(p) = b
a =
0 0 1 1 0 0
LUI PAUL
2015-4-3
its not mentioned 'logical'.Chris said only vector....logical may not be used....
James Tursa
2015-4-3
Go to Adam's answer. Read the 5th and 6th comments by Chris and Adam. They clearly show that the fundamental issue is that "a" is logical, and Adam posts a solution for this that works when "a" is logical.
for logical a,...try this
a = logical([0 0 1 1 0 0]);
a=double(a);
b = [5 6];
p = find(a>0);
a(p) = b
a =
0 0 5 6 0 0
what do you think @James will it work?
James Tursa
2015-4-3
Yes.
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