Access the data from a Struct
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I have a struct with fields
val = struct with fields:
abstract: [1×1 struct]
body_text: [72×1 struct]
when I extract the text data in body_text using "val.body_text.text" I got 72*1 struct. But when I try "A = val.abstract.text", I got only the first struct of the 72 structs. How can I put all these [72×1 struct] into A?
Thanks!
3 个评论
dpb
2020-3-30
"when I try "A = val.abstract.text"
But
val = struct with fields:
abstract: [1×1 struct]
body_text: [72×1 struct]
so val.abstract.text is either invalid reference or is the name of the 1x1 struct under val.abstract
The array of 72 stuct is contained in the val struct field .body_text
It isn't clear why you think there should be more than one element from the reference above...of course, we can't see what the content of these embedded struct is so we've no idea what are fieldnames thereof.
Seems like a very convoluted nested storage--my first recommendation would be to see if you can't somehow simplify this drastically.
Ameer Hamza
2020-3-30
''so val.abstract.text is either invalid reference or is the name of the 1x1 struct under val.abstract'''
Not necessarily. For example
>> s.text = '123';
s.xyz = 2;
val.abstract = s;
val.body_text = repmat(s, 1, 72);
>> val
val =
struct with fields:
abstract: [1×1 struct]
body_text: [1×72 struct]
>> val.abstract.text
ans =
'123'
Susan
2020-3-30
采纳的回答
Ameer Hamza
2020-3-30
编辑：Ameer Hamza
2020-3-30
Try this, if the data in the field 'text' is scalar
A = [val.abstract.text];
If it is vector than try
A = {val.abstract.text};
5 个评论
Susan
2020-3-30
Ameer Hamza
2020-3-30
Glad to be of help.
Susan
2020-3-30
Ameer Hamza
2020-3-31
Try the following code. Place it one directly above the JSON files, or you can modify the first line according to the path of your JSON files. It will read all files, and gather their abstract.text and body_text.text fields into one struct. It then writes the final struct as a JSON file.
files = dir('JSON files/*.json');
s = struct('abstract', [], 'body_text', []);
for i=1:numel(files)
filename = fullfile(files(i).folder, files(i).name);
data = jsondecode(fileread(filename));
if ~isempty(data.abstract)
s.abstract = [s.abstract; cell2struct({data.abstract.text}, 'text', 1)];
end
if ~isempty(data.body_text)
s.body_text = [s.body_text; cell2struct({data.body_text.text}, 'text', 1)];
end
end
str = jsonencode(s);
f = fopen('filename.json', 'w');
fprintf(f, '%s', str);
fclose(f);
Susan
2020-3-31
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