How can extract specific value from a column contains 3 conditions

Hello,

I faced problem of separating the data in .csv file. I have huge data consiste of 81 csv, and each file consists of 887808x74 matrix. My work depends on separted 3 conditions (labels) based on third column which has condition 1 , condition 2, and condition 3. I want to put each condition togethor for example condition 1 with all information that related in other columns togethor and so on for other conditions. i tried to do it by myself but not work.

If any one has idea to help me i will appretiate that. it can find out the sample of the file in attachment.

Regards,

Answer 1

[Peng Li]

I assume that you are using datastore and tall array.

Suppose tb is your tall table. You can use tb1 = tb(tb.(3) == 1, :) to get a subtable that has condition 1 on the third column. and similarly use tb(tb.(3) == 2, :) to get a subtable that has condition 2.

Is this what you want?

[Noura Saleh]

what do you mean by datastore?

i apply you suggestion but did not work.

what i want to create sub-matrices based on the three conditions that existed in the main matrix.

[Peng Li]

using your example file as an example:

tb = readtable('example file.xlsx', 'ReadVariableNames', 0);
tb1 = tb(tb.(3) == 1, :);
tb2 = tb(tb.(3) == 2, :);
tb3 = tb(tb.(3) == 3, :);

If you are not using a table variable, you could easily adjust your syntax using tb(:, 3) == 1 for example. I prefer using table.

[Noura Saleh]

thank you for your help , i whish if you can see my problem now ,

i tried the following line of code, sence my file in csv file and i want to work with this extentions

T = csvread('hc.csv');

tb1 = T(T.(3) == 1, :);

it show me an error

[Argument to dynamic structure reference must evaluate to a valid field name.

Error in Readcsv1 (line 21)

tb1 = T(T.(3) == 1, :);]

for that i used used your sggusted code

T = readtable('hc.csv', 'ReadVariableNames', 0);

tb1 = T(T.(3) == 1, :);

it works , but when i tried to save i file into csv file and load it again to matlab dose not work?? by this line

save('tb1.csv');

the message error:

[Error using dlmread (line 147)

Mismatch between file and format character vector.

Trouble reading 'Numeric' field from file (row number 1, field number 1) ==> MATLAB 5.0 MAT-file, Platform:

PCWIN64, Created on: Sat Mar 28 16:49:40 2020 & IM I xϋc``h b6

æ bA`Â0ÍÂàëìd³qIbRN*æb$}¼P}¬P>X/3@ùæ]&...

Error in csvread (line 48)

m=dlmread(filename, ',', r, c);]

please could you help me if the problem clear

thanks,

[Peng Li]

Using writetable instead to save table to csv or txt or xlsx.