Hi,
I've got a matrix with about 1 million rows and 1 column. I need to resize it so it only has 500,000 rows. How do you 'crop' a matrix in matlab?
Thanks
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Note: What I wrote above assumes that you have exactly 1 million rows. If not, you need to either modify the number of rows and columns in the command (for example, if you have 1200000 rows, use reshape(A,600000,2) or reshape(A,400000,3) and so on) or "pad" the vector (e.g., add zeroes until the vector has 1 million rows)
a=[2 2;2 2]
b=reshape(a,1,4)
now b will be [2 2 2 2]. You can re-size using the reshape function.
Generate command
reshape(input,m,n) here input m.n specifies the dimension of the resulting matrix.
Note:
While resizing the source dimension should not be mismatched.
i.e when source has 1x64
it can be converted to 8x8
or 32x2 or any combination like that.
And it is meaning less if you mention 3x8
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by: Eyal-fPosted on 2008-12-04 at 23:55:20ID: 23103112
I'm not sure exatcly what you want to do. Do you want to just cut off the last 500,000 lines? If so, use (if A is your matrix)
A=A(1:500000)
or
A(500001:1000000)=[]
or whatever other indices you want to keep (in the first case) or discard (in the second).
If you want to keep all the data, you can use reshape. I don't have Matlab in front of me at the moment, but it should be something like A=reshape(A,500000,2)
Alternatively, a clunkier version would be
A=[A(1:500000,1),A(500001: