Insert data to table

Question

Indrani 2023-10-24

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2038026-insert-data-to-table

评论： Indrani 2023-10-26

Hi,

I have a table temps with 2 columns of type DateTime and Double. In the Double column of the table, I have manually inserted from values (the first 90 rows). I want to populate the next rows of the Double column with values from a different table which has only 1 column.

How do I proceed?

Thanks!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Voss 2023-10-24

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2038026-insert-data-to-table#answer_1339706

在 MATLAB Online 中打开

temps = table(datetime(rand(10,1),'ConvertFrom','datenum'),rand(10,1))
temps = 10×2 table
            Var1               Var2   
    _____________________    _________

    31-Dec--0001 05:25:55       0.5695
    31-Dec--0001 05:53:09    0.0014856
    31-Dec--0001 00:43:32      0.97354
    31-Dec--0001 01:51:05       0.3349
    31-Dec--0001 10:14:34      0.39485
    31-Dec--0001 13:05:17      0.47122
    31-Dec--0001 10:17:15      0.39123
    31-Dec--0001 22:40:54      0.32628
    31-Dec--0001 01:09:12       0.4325
    31-Dec--0001 21:27:43      0.73325
a_different_table = table([1;2;3;4;5])
a_different_table = 5×1 table
    Var1
    ____

     1  
     2  
     3  
     4  
     5  
start_row = 6;
temps{start_row+(0:size(a_different_table,1)-1),2} = a_different_table{:,1}
temps = 10×2 table
            Var1               Var2   
    _____________________    _________

    31-Dec--0001 05:25:55       0.5695
    31-Dec--0001 05:53:09    0.0014856
    31-Dec--0001 00:43:32      0.97354
    31-Dec--0001 01:51:05       0.3349
    31-Dec--0001 10:14:34      0.39485
    31-Dec--0001 13:05:17            1
    31-Dec--0001 10:17:15            2
    31-Dec--0001 22:40:54            3
    31-Dec--0001 01:09:12            4
    31-Dec--0001 21:27:43            5

3 个评论
显示 1更早的评论隐藏 1更早的评论

Voss 2023-10-24

在 MATLAB Online 中打开

The code in my answer places the values from the second table into the second column of the first table starting with the specified start_row. If the values from the second table would extend the first table when placed in it, then that's what happens (the code is the same); if the values from the second table would not reach to the bottom of the first table when placed there then that's what happens (the code is still the same). Here are some additional examples so you can see better how it works.

Case 1: adding values extends the table:

temps = table(datetime(rand(10,1),'ConvertFrom','datenum'),rand(10,1))
temps = 10×2 table
            Var1               Var2  
    _____________________    ________

    31-Dec--0001 01:51:10     0.21545
    31-Dec--0001 08:39:59     0.30481
    31-Dec--0001 01:18:19     0.20133
    31-Dec--0001 14:25:10      0.7748
    31-Dec--0001 15:55:34     0.40753
    31-Dec--0001 14:06:46     0.90364
    31-Dec--0001 04:29:18      0.4439
    31-Dec--0001 10:31:34     0.47939
    31-Dec--0001 17:24:58     0.31158
    31-Dec--0001 08:22:42    0.042024
a_different_table = table([1;2;3;4;5;6])
a_different_table = 6×1 table
    Var1
    ____

     1  
     2  
     3  
     4  
     5  
     6  
start_row = 6;
temps{start_row+(0:size(a_different_table,1)-1),2} = a_different_table{:,1}
Warning: The assignment added rows to the table, but did not assign values to all of the table's existing variables. Those variables are extended with rows containing default values.
temps = 11×2 table
            Var1              Var2  
    _____________________    _______

    31-Dec--0001 01:51:10    0.21545
    31-Dec--0001 08:39:59    0.30481
    31-Dec--0001 01:18:19    0.20133
    31-Dec--0001 14:25:10     0.7748
    31-Dec--0001 15:55:34    0.40753
    31-Dec--0001 14:06:46          1
    31-Dec--0001 04:29:18          2
    31-Dec--0001 10:31:34          3
    31-Dec--0001 17:24:58          4
    31-Dec--0001 08:22:42          5
                      NaT          6

Case 2: adding values does not extend the table:

temps = table(datetime(rand(10,1),'ConvertFrom','datenum'),rand(10,1))
temps = 10×2 table
            Var1               Var2  
    _____________________    ________

    31-Dec--0001 18:06:52     0.15185
    31-Dec--0001 23:43:46     0.25475
    31-Dec--0001 15:50:34     0.14091
    31-Dec--0001 05:20:51     0.77864
    31-Dec--0001 20:00:06     0.61666
    31-Dec--0001 06:57:24    0.063698
    31-Dec--0001 07:49:50     0.41166
    31-Dec--0001 12:17:34     0.92858
    31-Dec--0001 19:35:11     0.36186
    31-Dec--0001 07:24:06     0.66432
a_different_table = table([1;2;3;4])
a_different_table = 4×1 table
    Var1
    ____

     1  
     2  
     3  
     4  
start_row = 6;
temps{start_row+(0:size(a_different_table,1)-1),2} = a_different_table{:,1}
temps = 10×2 table
            Var1              Var2  
    _____________________    _______

    31-Dec--0001 18:06:52    0.15185
    31-Dec--0001 23:43:46    0.25475
    31-Dec--0001 15:50:34    0.14091
    31-Dec--0001 05:20:51    0.77864
    31-Dec--0001 20:00:06    0.61666
    31-Dec--0001 06:57:24          1
    31-Dec--0001 07:49:50          2
    31-Dec--0001 12:17:34          3
    31-Dec--0001 19:35:11          4
    31-Dec--0001 07:24:06    0.66432

Voss 2023-10-24

编辑：Voss 2023-10-24

在 MATLAB Online 中打开

"I do not want a separate column Var3. Is it possible to enter values of table T2 in the column Var2, after the last value of table T1?"

Using the code from my answer and setting the start_row to be size(T1,1)+1, i.e., start right after the last value of T1.

T1 = table(datetime(rand(7,1),'ConvertFrom','datenum'),rand(7,1))
T1 = 7×2 table
            Var1              Var2  
    _____________________    _______

    31-Dec--0001 09:58:55    0.29951
    31-Dec--0001 20:12:04    0.82653
    31-Dec--0001 06:15:31     0.1411
    31-Dec--0001 12:22:05    0.96888
    31-Dec--0001 14:49:06    0.92325
    31-Dec--0001 07:30:46    0.18036
    31-Dec--0001 15:18:23    0.33511
T2 = table([1;2;3])
T2 = 3×1 table
    Var1
    ____

     1  
     2  
     3  
start_row = size(T1,1)+1;
T1{start_row+(0:size(T2,1)-1),2} = T2{:,1}
Warning: The assignment added rows to the table, but did not assign values to all of the table's existing variables. Those variables are extended with rows containing default values.
T1 = 10×2 table
            Var1              Var2  
    _____________________    _______

    31-Dec--0001 09:58:55    0.29951
    31-Dec--0001 20:12:04    0.82653
    31-Dec--0001 06:15:31     0.1411
    31-Dec--0001 12:22:05    0.96888
    31-Dec--0001 14:49:06    0.92325
    31-Dec--0001 07:30:46    0.18036
    31-Dec--0001 15:18:23    0.33511
                      NaT          1
                      NaT          2
                      NaT          3