create a array base on specific condition ?
显示 更早的评论
I had a array like this
A=[0 0 0 10 0 0 0 0 8 0 0 5 0 0 0 3 0 2 0 0 0 1 0 0 0];
and now I want to create a array B like this in which
B(4)=10-8=2;
[B(4)=A(4)-next upcoming non zero value ],
B(9)=8-5=3;[B(9)=A(9)-next non zero value]
and similarly for
B(12)=5-3=2;
B(16)=3-2=1;
B(18)=2-1=1;
B(22)=1;
and rest of the B values are zero. thanks
采纳的回答
>> idx = A~=0;
>> A(idx) = [-diff(A(idx)),1]
A =
0 0 0 2 0 0 0 0 3 0 0 2 0 0 0 1 0 1 0 0 0 1 0 0 0
5 个评论
jonas
2018-8-30
+1 always quick with the efficient solution :)
Stephen23
2018-8-30
@jonas: thank you.
MUKESH KUMAR
2018-8-31
编辑：MUKESH KUMAR
2018-8-31
@MUKESH KUMAR: you get negative values because although in your question you gave values which decrease in magnitude (so their differences are all positive), in your real A data all of the values increase in magnitude (so their differences are all negative). Lets have a look at some of the values:
>> B(find(B))
ans =
-1
-5
-3
-2
... lots more here
-3
-2
1
>> A(find(A))
ans =
1
2
7
10
12
13
... lots more here
128
131
133
In your question you wrote: "I had a array like this"
A=[0 0 0 10 0 0 0 0 8 0 0 5 0 0 0 3 0 2 0 0 0 1 0 0 0];
"and now I want to create a array B like this in which"
B(4)=10-8=2;
[B(4)=A(4)-next upcoming non zero value ],
B(9)=8-5=3;[B(9)=A(9)-next non zero value]
Lets try your exact calculation method with the real A values:
B(6334) = A(6334) - A(6478) = -1
B(6478) = A(6478) - A(7487) = -5
B(7487) = A(7487) - A(7543) = -3
...etc
All are negative, all follow the method that you gave in your question, and all are exactly the values that are in B.
MUKESH KUMAR
2018-8-31
更多回答（1 个）
jonas
2018-8-30
v=A(find(A~=0));
vid=find(A~=0);
B=A
B(vid)=B(vid)-[v(2:end) 0]
not the most elegant solution
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