Read in json file as three dimensional array

Hello,

I have trouble with Matlab and reading data from JSON files. I basically have one .json file which looks like this:

{
    "Data": {
        "1": [
            0.0,
            0.1,
            0.2,
            0.3,
            0.4,
            0.5,
            0.6,
            0.7,
            0.8,
            0.9,
            1.0
        ],
        "2": [
            3.1517,
            3.4879332128,
            3.551222604,
            3.5870886304,
            3.6319243674,
            3.6911242439,
            3.7654878049,
            3.8551335026,
            3.960078832,
            4.0803263235,
            4.2158762895
        ],
        "3": [
            3.4262,
            3.5204004756,
            3.5719092392,
            3.6113550565,
            3.6542077094,
            3.7082794455,
            3.777514335,
            3.8639024635,
            3.9684468861,
            4.0916520841,
            4.2337707085
        ]
    }
}

Then in my Matlab code I try to read this data with:

fname = 'test.json';
fid = fopen(fname);
raw = fread(fid,inf);
str = char(raw');
fclose(fid);
jsonData = jsondecode(str);

Sadly all the data is then in a single dimensional array but I would need each data tab as one array, so that later on I can use it as "jsonData.("1")".

Where is the error in my code? Still at the beginning of using Matlab as you can probably guess my looking at my question.

Answer 1

[Eshaan Shah]

Hi,

I executed the following code in MATLAB 19b and it seems to work as expected.

fname = 'test.json';
fid = fopen(fname);
raw = fread(fid,inf);
str = char(raw');
fclose(fid);
jsonData = jsondecode(str);

Below is the content of jsonData:

>> jsonData

jsonData = 

  struct with fields:

    Data: [1×1 struct]

>> jsonData.Data

ans = 

  struct with fields:

    x1: [11×1 double]
    x2: [11×1 double]
    x3: [11×1 double]

In order to correctly access the individual arrays, you can execute

jsonData.Data.x1
jsonData.Data.x2
jsonData.Data.x3

Note: I see the same behavior in 19a, 19b, 20a, and 20b.

[Nitesh Panchal]

>> fname = 'test.m';

>> fid = fopen(fname);

>> raw = fread(fid,inf);

>> str = char(raw');

>> fclose(fid);

>> jsonData = jsondecode(str);

>> jsonData

jsonData =

struct with fields:

Data: [1×1 struct]

>> jsonData.Data

ans =

struct with fields:

x1: [11×1 double]

x2: [11×1 double]

x3: [11×1 double]

>> jsonData.Data,x1

ans =

struct with fields:

x1: [11×1 double]

x2: [11×1 double]

x3: [11×1 double]

Undefined function or variable 'x1'.

>> jsonData.Data.x1

ans =

0

0.1000

0.2000

0.3000

0.4000

0.5000

0.6000

0.7000

0.8000

0.9000

1.0000

>>