cell array indexing oddity

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Robert Scott 2021-7-29

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回答： Image Analyst 2021-7-29

i have a large cell array of type cell

when i do this

test{2:2:end,7} i get back cells

when i do this i get back ints that are in the cell

test{1,1}

Its very frustrating, I wanted to access all the rows from 2 to the end skipping one in the midding of col 7

Why is that so hard?

It works for a single instance but cant do it in a vectorized form

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Robert Scott 2021-7-29

编辑：Robert Scott 2021-7-29

K>> test{2:2:end,7}*1

Error using *

Too many input arguments.

DGM 2021-7-29

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A = num2cell(reshape(1:70,10,[]))
A = 10×7 cell array
    {[ 1]}    {[11]}    {[21]}    {[31]}    {[41]}    {[51]}    {[61]}
    {[ 2]}    {[12]}    {[22]}    {[32]}    {[42]}    {[52]}    {[62]}
    {[ 3]}    {[13]}    {[23]}    {[33]}    {[43]}    {[53]}    {[63]}
    {[ 4]}    {[14]}    {[24]}    {[34]}    {[44]}    {[54]}    {[64]}
    {[ 5]}    {[15]}    {[25]}    {[35]}    {[45]}    {[55]}    {[65]}
    {[ 6]}    {[16]}    {[26]}    {[36]}    {[46]}    {[56]}    {[66]}
    {[ 7]}    {[17]}    {[27]}    {[37]}    {[47]}    {[57]}    {[67]}
    {[ 8]}    {[18]}    {[28]}    {[38]}    {[48]}    {[58]}    {[68]}
    {[ 9]}    {[19]}    {[29]}    {[39]}    {[49]}    {[59]}    {[69]}
    {[10]}    {[20]}    {[30]}    {[40]}    {[50]}    {[60]}    {[70]}
A{2:2:end,7} % output is multiple scalars
ans = 62
ans = 64
ans = 66
ans = 68
ans = 70
vertcat(A{2:2:end,7}) % output is a single column vector
ans = 5×1
    62
    64
    66
    68
    70

You need to deal with the fact that that expression has multiple outputs.

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Image Analyst 2021-7-29

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I know you said you tried using cell2mat(), but you must have not used it correctly. Try using cell2mat() like this:

test = num2cell(reshape(1:80,10,[])) % 10 rows by 8 columns
% Take contents of 7th column and even numbered rows.
% 7th column has 10 elements.
out = cell2mat(test(:,7)); % Get 7th column.
out = out(2:2:end) % Every other element to give 5 elements.
whos test
whos out