how to split table with different time values

Question

uzzi 2022-11-2

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https://ww2.mathworks.cn/matlabcentral/answers/1841908-how-to-split-table-with-different-time-values

评论： uzzi 2022-11-18

Hello,

I have an attached table with time column (hh:mm:ss) and a data column. I'd like to make separate columns or tables according to the different time (minutes) and plot seperate figures for that.

I attached the ''csv'' file here. Can someone help me, pls?

a = readtable('tb.csv')
a = 675×2 table
timeVar1________________

46:13     -27.426
46:13     -12.221
46:13      15.665
46:13     -27.113
46:13     -12.416
46:13     -1.3964
46:13      16.638
46:14     -25.833
46:14     -10.794
46:14    -0.43471
46:14      17.373
46:14     -17.638
46:14     -7.1675
46:14       10.33
46:14        20.7
46:15      -26.28

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Dyuman Joshi 2022-11-2

Minutes meaning minute of the hour? or from a reference time?

uzzi 2022-11-2

编辑：uzzi 2022-11-2

Minutes means by minutes of the hour. As shown in figure taken from the attached csv table, there are multiple seconds for 14 hour 46 minutes. I want to plot for 14 hour 46 minutes and 15 hour 02 minutes, etc. separately.

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Answer 1

Dyuman Joshi 2022-11-2

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1841908-how-to-split-table-with-different-time-values#answer_1089893

编辑：Dyuman Joshi 2022-11-2

在 MATLAB Online 中打开

tb.csv

Finding the indices where the minute starts/changes/ends -

a = readtable('tb.csv');
[~,~,~,h,m,~]=datevec(a.time);
y=unique([1 find(diff(m)~=0)'+1 numel(m)+1])
y = 1×8
     1   150   236   397   503   526   658   676

You can convert the data in different individual elements like this -

z=mat2cell(a.Var1,diff(y),1)

z = 7×1 cell array

{149×1 double} { 86×1 double} {161×1 double} {106×1 double} { 23×1 double} {132×1 double} { 18×1 double}

%you can plot directly as well

for i=1:numel(y)-1

figure

arr=y(i):y(i+1)-1;

plot(a.time(arr),a.Var1(arr),'color', rand(1,3))

end

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uzzi 2022-11-2

Thanks a ton, Dyuman Joshi. I understood it now. Your explanation is very clear.

I was trying this since morning and I couldn't crack it. You made my day :)

Dyuman Joshi 2022-11-2

You are welcome!

Glad to have helped.

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Answer 2

Lei Hou 2022-11-18

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1841908-how-to-split-table-with-different-time-values#answer_1103363

在 MATLAB Online 中打开

Hi,

Datevec is in discourage use now. You can use retime to group your data and do plot.

>> tt = readtimetable('tb.csv')
tt =
  675×1 timetable
      time       Var1  
    ________    _______
    14:46:13    -27.426
    14:46:13    -12.221
    14:46:13     15.665
    14:46:13    -27.113
    14:46:13    -12.416
       :           :   
    15:58:02     2.4096
    15:58:02     12.741
    15:58:02     7.5679
    15:58:02      11.63
    15:58:02     6.6887
	Display all 675 rows.
>> tt1 = retime(tt,"minutely",@(x){x})
tt1 =
  73×1 timetable
      time           Var1     
    ________    ______________
    14:46:00    {149×1 double}
    14:47:00    {  0×1 double}
    14:48:00    {  0×1 double}
    14:49:00    {  0×1 double}
    14:50:00    {  0×1 double}
       :              :       
    15:54:00    {  0×1 double}
    15:55:00    {  0×1 double}
    15:56:00    {  0×1 double}
    15:57:00    {132×1 double}
    15:58:00    { 18×1 double}
	Display all 73 rows.
>> tt2 = tt1(cellfun(@(x)~isequal(x,double.empty(0,1)),tt1.Var1),:)
tt2 =
  7×1 timetable
      time           Var1     
    ________    ______________
    14:46:00    {149×1 double}
    15:02:00    { 86×1 double}
    15:27:00    {161×1 double}
    15:35:00    {106×1 double}
    15:48:00    { 23×1 double}
    15:57:00    {132×1 double}
    15:58:00    { 18×1 double}