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Selecting particular data range from table/ columns

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Hi there,
I am very new to Matlab and haven't been able to find the following solution.
I have two columns within a table of 1537090 x 2. Within the second column I want to extract numbers that fall within a range of 15 to 50.
Any numbers that are found in that range in column 2 I would like the corresponding row from Column 1 to also be pulled out.
The result will be another two column table but have all values within 15 to 50 from Column 2 and the corresponding rows from Column 1.
Thanks very much in advance and really appreciate any help.

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Accepted Answer

Star Strider
Star Strider on 18 Apr 2020
Try this:
T1 = table(rand(100,1), randi(75,100,1)); % Original Table
L = table2array(varfun(@(x)((x>=15) & (x<=50)), T1(:,2))); % Logical Vector
T2 = T1(L,:); % Edited Table
.

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Star Strider
Star Strider on 20 Apr 2020
I am getting the expected result:
D = load('Temp_Rain table.mat');
Temp_Rain = D.Temp_Rain;
L = table2array(varfun(@(x)((x>=15) & (x<=50)), Temp_Rain(:,2)));
Temp_Rain_2 = Temp_Rain(L,:);
Then checking:
Before = Temp_Rain(1:10,:)
After = Temp_Rain_2(1:10,:)
produces:
Before =
10×2 table
VarName2 VarName3
________ ________
31.447 69.79
33.191 83.479
34.808 88.95
30.423 65.394
31.536 96.773
32.559 93.525
36.026 109.91
36.716 35.646
28.261 52.139
28.536 18.59
After =
10×2 table
VarName2 VarName3
________ ________
36.716 35.646
28.536 18.59
34.459 48.416
35.179 23.567
30.255 18.303
34.349 19.674
28.64 26.635
28.655 47.264
28.712 21.465
35.886 31.472
Other than what I already mentioned, I have no idea what could cause the problem you are seeing.
.
Tyson Campbell
Tyson Campbell on 20 Apr 2020
I reran the code using what you just sent through then and it worked! Temp_Rain_2 resulted in a table of 419751x2. Thanks so much for all your efforts.
Star Strider
Star Strider on 20 Apr 2020
As always, my pleasure!
(That was the same result I got.)

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More Answers (1)

Sindar
Sindar on 18 Apr 2020
Edited: Sindar on 18 Apr 2020
idx = (mytable{:,2} >= 15) & (mytable{:,2} <= 50);
newtable = mytable(idx,1:2);
Components of the answer:
  • extract the data in the 2nd column (note {}; () would return a table)
mytable{:,2}
  • identify which elements of this array (i.e. which rows of the table) are >= 15. This returns a logical array (true where >=15, false elsewhere)
(mytable{:,2} >= 15)
  • elementwise AND with the other condition (<=50) so true only in the range
() & ()
  • extract the appropriate rows from the table (and columns, though ":" would work as well if you want all the columns)
mytable(idx,1:2)

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