Dot notation from string

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Vit Krcal
Vit Krcal on 31 Mar 2020
Commented: Stephen23 on 1 Apr 2020
Hi,
Is there any way to convert string with dots do a dot notation?
Let S be a structure, I want to get
I store a "path" to field to a string
path = ['field1.field2.field3'];
I want to get to a specified field3, instead of
S.field1.field2.field3
I want to call it like this, without separating it by dots.
S.(path)
If I put it like this, it treats the whole string like one name of field.
The reason is that I use a loop which creates the string "path", depending on existance of fields in each "depth" - the substructures are inconsistent. I want the "depth" (number of dots) to be variable.
THX
  3 Comments
Vit Krcal
Vit Krcal on 31 Mar 2020
Thanks a lot!
Stephen23
Stephen23 on 1 Apr 2020
@Peng Li: due to the disadvantages of eval that approach is not recommended.

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Accepted Answer

Steven Lord
Steven Lord on 31 Mar 2020
DON'T use eval. There's no need to use it in this case anyway. split the text representation of the nested fields into pieces then pass those pieces into getfield as a comma-separated list.
S.field1.field2.field3 = 42;
P = 'field1.field2.field3';
pathPieces = split(P, '.');
theAnswer = getfield(S, pathPieces{:})
Things get trickier if you have a more complicated indexing expression, but take a look at the help and documentation for getfield for how to handle such situations.

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