How to set Time Axis

Question

Abhishek Savita 2017-12-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/373075-how-to-set-time-axis

评论： Abhishek Savita 2017-12-20

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

Hi Folks

I have a data in which time axis set in following format

       ncdisp('myfile.nc')
       time              
           Size:       39x1
           Dimensions: time
           Datatype:   single
           Attributes:
                       standard_name = 'time'
                       long_name     = 'time'
                       units         = 'months since 1970-01-01 00:00:00'
                       axis          = 'T'
                       climatology   = 'climatology_bounds'
      year=ncread('myfile.nc','time')
      year=
    9×1 single column vector
     6
    18
    30
    42
    54
    66
    78
    90
   102
   114
   126
   138
   150
   162
   174
   186
   198
   210
   222
   234
   246
   258
   270
   282
   294
   306
   318
   330
   342
   354
   366
   378
   390
   402
   414
   426
   438
   450
   462

But i want to convert variable year(6,18,30,...,462) to year(1:39), which represent 1 as 1970 and 39 as 2008;

I mean

year(1)=1970
year(2)=1971 
.
.
.
year(39)=2008

Could you please suggest me, how can I make it ?

Thanks in advance

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Answer 1

Walter Roberson 2017-12-20

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https://ww2.mathworks.cn/matlabcentral/answers/373075-how-to-set-time-axis#answer_297058

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ncmon = ncread('myfile.nc','time');
year = 1970 + floor((ncmon - 1) / 12);

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Abhishek Savita 2017-12-20

编辑：Walter Roberson 2017-12-20

在 MATLAB Online 中打开

Hi James and walter thank you for your reply; I am doing following steps in the matlab to store my data variable time in year(6 18,30,...) to year(1970,1971...)

ncdisp('myfile.nc');
time              
           Size:       39x1
           Dimensions: time
           Datatype:   single
           Attributes:
                       standard_name = 'time'
                       long_name     = 'time'
                       units         = 'months since 1970-01-01 00:00:00'
                       axis          = 'T'
                       climatology   = 'climatology_bounds'
h18_hc            
           Size:       360x180x1x39
           Dimensions: lon,lat,depth,time
           Datatype:   single
           Attributes:
year=ncread('myfile.nc','time');
ohc=ncread('myfile.nc','h18_hc'
whos year
Name       Size            Bytes  Class     Attributes
    year      39x1               156  single
whos h18_hc
  Name          Size                     Bytes  Class     Attributes
    h18_hc      360x180x1x39            20217600  double 
year =
    39×1 single column vector
       6
      18
      30
      42
      54
      66
      78
      90
     102
     114
     126
     138
     150
     162
     174
     186
     198
     210
     222
     234
     246
     258
     270
     282
     294
     306
     318
     330
     342
     354
     366
     378
     390
     402
     414
     426
     438
     450
     462
  year_new=1970+floor((year-1)/12);
  year_new=double(year_new)
  ohc_18_new=h18_hc(:,:,:,year_new);

Whem am I doing this i am getting following error

Index exceeds matrix dimensions.

I hope i will get some solution from you, I am very new in matlab.

Thanks in advance

Walter Roberson 2017-12-20

在 MATLAB Online 中打开

ncmon = ncread('myfile.nc','time');
year_index = 1 + floor((ncmon - 1) / 12);
calendar_year = 1970 + year_index - 1;
ohc_18_new=h18_hc(:,:,:,year_index);

Abhishek Savita 2017-12-20

Thank you very much Walter, it is now.

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Answer 2

James Knowles 2017-12-20

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https://ww2.mathworks.cn/matlabcentral/answers/373075-how-to-set-time-axis#answer_297055

在 MATLAB Online 中打开

I am sure there is a more elegant and simpler solution out there but this will function as you desire.

year = [6
    18
    30
    42
    54
    66
    78
    90
   102
   114
   126
   138
   150
   162
   174
   186
   198
   210
   222
   234
   246
   258
   270
   282
   294
   306
   318
   330
   342
   354
   366
   378
   390
   402
   414
   426
   438
   450
   462];
YEAR = zeros(39,1); %this will become the vector you desire
for i=1:39 
    years_passed = floor(year(i)/12);
    YEAR(i) = 1970+years_passed; 
end