How to fill the remaining "N" number of rows, of an already populated vector, with zeros

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Austin Sowers 2018-9-18

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评论： MF 2018-9-19

GV.mat

It may be confusing, so let me explain. The "GV" data I provided has values in it. It is size (18,001 x 1). I want the to fill the remaining "N" number of rows with zeros. So it may be a (20,000 x 1) or perhaps a (30,000 x 1) vector, but still with the first 18,001 rows filled with the "GV" values. How to do this??

Thank you in advance!

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Answer 1

MF 2018-9-18

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编辑：MF 2018-9-19

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Here is an example. 1) Let's first make a random vector of the size you have specified and 2) fill the vector with zeros so that it reaches 20000 rows.

GV=rand(18001,1);
GV(end+1:20000)=0;

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Austin Sowers 2018-9-18

A very good point. Thank you guys for your help!

MF 2018-9-19

Thank you dpb. The code was modified. I apologise for any inconveniences.

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Answer 2

Bruno Luong 2018-9-18

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编辑：Bruno Luong 2018-9-18

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% ... Compute GV
GV(20000)=0  % if you are sure 20000>length(GV), if not protect with IF

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dpb 2018-9-18

Good on ya', Bruno! :)

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Answer 3

dpb 2018-9-18

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Alternatively, and perhaps more efficient depending upon how GV is generated/obtained...

GV(Ntotal,1)=0;                % preallocate (could also write zeros(Ntotal,1) )
GV(1:N)=GVcalculation(1:N);    % put the calculation results in first N locations

Which way is more effective depends on the details we don't know...