MATLAB Answers

Extracting table from data structure

조회 수: 24(최근 30일)
Haresh Kumar
Haresh Kumar 6 Apr 2021
댓글: Haresh Kumar 6 Apr 2021
Hello,
I have multile .mat files and from these files I want to extract the table with variable name B (500000×1 double). At first, I have loaded data using S = dir('*.mat'); and then I am using commond K = S.B; to extract the data from table variable name B. This commond doesnot work and gave me this message: Reference to non-existent field 'B'.. Can you guide me which commond will I use to extract the table data from data structure.
Br,
Haresh Kumar
  댓글 수: 4
Haresh Kumar
Haresh Kumar 6 Apr 2021
Hello,
Let me make it simple. I am giving directory path inorder to run the multiple .mat files from the folder. Each .mat file (number (1)......number(n)) contains multiple tables from which I only want the table of variable B. Now, you can guide which commond will I use to get the data from variable B (Table)
Br,
Haresh Kumar

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답변(2개)

Hiro
Hiro 6 Apr 2021
First thing you should do is check if S is a table variable.
If it turns out to be a table variable, then the next thing would be running the following command to check if B exists
S.Properties.VariableNames
Good luck.
  댓글 수: 3
Haresh Kumar
Haresh Kumar 6 Apr 2021
name
folder
date
bytes
isdir
datenum

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Steven Lord
Steven Lord 6 Apr 2021
At first, I have loaded data using S = dir('*.mat');
The dir function does not load data. All it does is generate a list of files in the directory with the .mat extension. To load the data you'll need to use the load function. Then if you want to check if the loaded data contains a variable named B (that has been loaded into a field of the output of load you can use isfield.
data = load('census.mat')
data = struct with fields:
cdate: [21×1 double] pop: [21×1 double]
doesItHaveAVariableB = isfield(data, 'B')
doesItHaveAVariableB = logical
0
doesItHaveAVariableCdate = isfield(data, 'cdate')
doesItHaveAVariableCdate = logical
1

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