Find the first matched string/value from a table

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Kane Lok 2023-6-13

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https://ww2.mathworks.cn/matlabcentral/answers/1982404-find-the-first-matched-string-value-from-a-table

评论： Star Strider 2023-6-15

采纳的回答： Star Strider

Hi,

I have got a table like below:

StepNum Activity TypeNum

5098 Stand 1-96

5099 Stand 1-96

5101 Stationary 1-96

5105 Stationary 1-96

5106 Stand 1-97

5107 Stand 1-97

5113 Stand 1-97

5114 Trenching 1-98

5115 Trenching 1-98

5116 Trenching 1-98

What I would like to do is to find the first matched of the string 'Trenching', then read the row/column number so that I can get the value/string in adjacent cells/rows. Just wondering if anyone here can help me out? Many thanks in advance.

Regards,

Kane

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Answer 1

Star Strider 2023-6-13

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https://ww2.mathworks.cn/matlabcentral/answers/1982404-find-the-first-matched-string-value-from-a-table#answer_1254899

在 MATLAB Online 中打开

One approach —

 VN = {'StepNum'  'Activity'  'TypeNum'}; 
 
 step = [5098 
 5099 
 5101  
 5105 
 5106 
 5107 
 5113 
 5114 
 5115 
 5116];
 
v23 = ["Stand"  "1-96" 
"Stand"  "1-96" 
"Stationary"  "1-96"  
"Stationary"  "1-96" 
"Stand"  "1-97" 
"Stand"  "1-97" 
"Stand"  "1-97" 
"Trenching"  "1-98" 
"Trenching" "1-98" 
"Trenching" "1-98"];
T1 = table(step, v23(:,1), v23(:,2), 'VariableNames',VN)
T1 = 10×3 table
    StepNum      Activity      TypeNum
    _______    ____________    _______

     5098      "Stand"         "1-96" 
     5099      "Stand"         "1-96" 
     5101      "Stationary"    "1-96" 
     5105      "Stationary"    "1-96" 
     5106      "Stand"         "1-97" 
     5107      "Stand"         "1-97" 
     5113      "Stand"         "1-97" 
     5114      "Trenching"     "1-98" 
     5115      "Trenching"     "1-98" 
     5116      "Trenching"     "1-98" 
idx = find(ismember(T1{:,2}, "Trenching"));
DesiredResult = T1{idx(1),:}                            % Contents Of Row
DesiredResult = 1×3 string array
    "5114"    "Trenching"    "1-98"
DesiredResult = T1(idx(1),:)                            % Sub-Table
DesiredResult = 1×3 table
    StepNum     Activity      TypeNum
    _______    ___________    _______

     5114      "Trenching"    "1-98" 

.

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Kane Lok 2023-6-14

编辑：Kane Lok 2023-6-14

Hi Star Strider,

Thanks for the help first.

The command of 'DesiredResult = T1{idx(1),:}' is not working, and I think it is down to the fact that I didn't explain my application thoroughly.

Basically I import a table from an excel file by using the following command:

data = readtable('InputFile.xlsx','Sheet','RecordInfo','range','A:K');

Once I have got 'data' in my MATLAB workspace, I then search for the first matched 'Trenching' and get the row number. So I could read the relevant TypeNum cell content and read other cell contents (like Volt and Current) in the previous rows (like stand and stationary) (i.e. the table that I posted intially is only a small part of the data).

StepNum Activity TypeNum Volt Current

_______ ____________ _______ ____ _______

5098 "Stand" "1-96" 1.1 0.1

5099 "Stand" "1-96" 1.2 0.2

5101 "Stationary" "1-96" 1.3 0.3

5105 "Stationary" "1-96" 1.3 0.3

5106 "Stand" "1-97" 1.8 0.8

5107 "Stand" "1-97" 2 0

5113 "Stand" "1-97" 1.9 1.9

5114 "Trenching" "1-98" 8 79

5115 "Trenching" "1-98" 11.5 80.5

5116 "Trenching" "1-98" 24 80.2

Those retrived cell content values will be used in a calculation to produce the results like R = (Volt(5114) - Volt(5113)) / (Current(5114) - Current(5113)). The calculated R will be used to produce another table.

Hopefully it is making sense to you and you are able to give me some suggestion? Thanks a lot.

Regards,

Kane

Kane Lok 2023-6-15

移动：Star Strider 2023-6-15

activity_table.xlsx

Hi Star Strider,

The excel file attached and thanks for your help.

Regards,

Kane

Star Strider 2023-6-15

在 MATLAB Online 中打开

activity_table.xlsx

My pleasure!

Try this (including a calculation for ‘R’) —

T1 = readtable('activity_table.xlsx', 'VariableNamingRule','preserve')
T1 = 2307×9 table
SignNumStepNameActivityStepNumLoopNumStepNumCurrent(A)Voltage(V)Power(W)RelativeTime(d.h:min:s.ms)___________________________________________________________________________________________________

       1       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:01:00.000'}    
       2       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:02:00.000'}    
       3       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:03:00.000'}    
       4       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:04:00.000'}    
       5       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:05:00.000'}    
       6       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:06:00.000'}    
       7       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:07:00.000'}    
       8       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:08:00.000'}    
       9       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:09:00.000'}    
      10       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:10:00.000'}    
      11       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:11:00.000'}    
      12       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:12:00.000'}    
      13       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:13:00.000'}    
      14       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:14:00.000'}    
      15       {'Stand'}        {'1-1'}           1          1           0           3.5253         0            {'0.00:15:00.000'}    
      16       {'Stand'}        {'1-1'}           1          1           0           3.5252         0            {'0.00:16:00.000'}    
VN = T1.Properties.VariableNames;
idx = find(ismember(T1{:,2}, "Trenching"))
idx = 1347×1
   930
   931
   932
   933
   934
   935
   936
   937
   938
   939
DesiredResult = T1(idx(1)+[-1 1],:)                            % Contents Of Row
DesiredResult = 2×9 table
    SignNum      StepName       ActivityStepNum    LoopNum    StepNum    Current(A)    Voltage(V)    Power(W)    RelativeTime(d.h:min:s.ms)
    _______    _____________    _______________    _______    _______    __________    __________    ________    __________________________

      929      {'Stand'    }        {'1-3'}           1          3              0          4.19            0         {'0.01:00:00.000'}    
      931      {'Trenching'}        {'1-4'}           1          4        -17.001        4.1828       -71.11         {'0.00:00:00.020'}    
Volt = DesiredResult{:,ismember(VN,'Voltage(V)')}
Volt = 2×1
    4.1900
    4.1828
Current = DesiredResult{:,ismember(VN,'Current(A)')}
Current = 2×1
         0
  -17.0006
R = (Volt(2) - Volt(1)) / (Current(2) - Current(1))
R = 4.2351e-04

See if that does what you want.

.

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Find the first matched string/value from a table

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