how to concatenate tables stored in a structure

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DuckDuck
DuckDuck 2018년 5월 11일
답변: Peter Perkins 2019년 5월 3일
I have a structure where tables with same variable names are stored. I want to concatenate all these tables in one big table.
say i have struct S
struct with fields:
T1: [34113×16 table]
T2: [34133×16 table]
T3: [34059×16 table]
T4: [33297×16 table]
T5: [34150×16 table]
I can do:
T=cat(1,T1,T2,T3,T4,T5)
but want to do it with listing struct fields and concatenate.
  댓글 수: 1
Stephen
Stephen 2018년 5월 11일
This would be a lot simpler with a non-scalar structure:
S(1).T = ...
S(2).T = ...
S(3).T = ...
...
then all you would need to do is:
cat(1,S.T)
Putting numbers into fieldnames just makes everything more complicated.

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채택된 답변

Guillaume
Guillaume 2018년 5월 11일
As Stephen commented, the initial designed is flawed. numbered variables and field names should always be replaced by a single container.
With a structure it's easily fixed by converting the structure into a cell array:
C = struct2cell(S);
vertcat(C{:}) %vertically concatenate all the fields of S
  댓글 수: 1
Jan
Jan 2018년 5월 17일
+1. If the data are represented as fields of a struct, this is the easiest solution. Stephen's comment showed, how to avoid a list of "numbered" fields by using a struct array. Alternatively you could store the tables in a cell array also: T{1}, T{2}, ... or if you need it: S.T{1}, S.T{2}, ... Then the concatenation is done again by:
vertcat(S.T{:}) % or vertcat(T{:})

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추가 답변(2개)

Peter Perkins
Peter Perkins 2019년 5월 3일
If you really ever only have five fields/tables in your scalar struct, just do this:
T=cat(1,S.T1,S.T2,S.T3,S.T4,S.T5)
But presumably you already knew that and you have either a large number of fields/tables, or a variable number. Try this (which uses numeric scalars instead of tables, but it's exactly the same):
>> s = struct; s.A = 1; s.B = 2; s.C = 3
s =
struct with fields:
A: 1
B: 2
C: 3
>> c = struct2cell(s)
c =
3×1 cell array
{[1]}
{[2]}
{[3]}
>> vertcat(c{:})
ans =
1
2
3

John BG
John BG 2018년 5월 11일
편집: John BG 2018년 5월 11일
Hi effess
there's no need to use the command cat or vertcat.
just concatenate the tables directly, like in the following example
1.
generating example data
var1=[1 2 3];var2=[4 5 6]
T1=table(var1,var2)
T2=T1
T3=T1
S(1).T=T1
S(2).T=T2
S(3).T=T3
2.
Since you clearly mentioned that all tables have the same variables, just put them all together like this:
T1=[S(1).T;S(2).T;S(3).T]
=
3×2 table
var1 var2
___________ ___________
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
.
effess
if you find this answer useful would you please be so kind to consider marking my answer as Accepted Answer?
To any other reader, if you find this answer useful please consider clicking on the thumbs-up vote link
thanks in advance for time and attention
John BG
  댓글 수: 7
Jan
Jan 2019년 4월 30일
@Rene Ferdinands: I've read your (meanwhile deleted) opinion about my "condescending" replies. Take into account, that this discussion has a background you are not aware of. Many contributions have been removed by the admins due to rudeness, so if you can see only my parts of the dicsussion, does not necessarily mean, that I was the aggressive part.
I appreciate that you care about the polite and friendly tone in the forum.

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