Unable to concatenate the table variables

I am using readtable command to read data from .csv file as given below. One of the column contains varying quantity, and I would like to specify those values in commandwindow. How can I achieve this.

In the below code, I am getting error saying ''Unable to concatenate the table variables''. How to resolve this?

Thank you

R1 = 0.02; R2 = 0.03;
my_data_1  = readtable('my_data.csv')
my_data_2 = table2array(my_data_1(:,1:4));

[Stephen23]

This is the entirety of what your file contains:

Sl. No.,f,t,Z
1,1,0,R1
2,1,2,R2
3,1,3,0.01+0.1j
4,3,2,0.02+0.2j

"How to resolve this"

Once you tell us what single variable type you expect to contain both numeric and text data, then you have your answer.

[ubaidulla]

R1 and R2 are of type "complex". That is values assigned to R1 and R2 are of class 'complex'.

[Stephen23]

"That is values assigned to R1 and R2 are of class 'complex'. "

MATLAB does not have a "complex" class type. Here are the fundamental MATLAB classes:

https://www.mathworks.com/help/matlab/matlab_prog/fundamental-matlab-classes.html

R1 could be char, or string, or categorical, or something similar.

[Walter Roberson]

The code is expecting that when the file is read, that any variable names in the text will be replaced with the value of the variable. However, MATLAB does not provide any file reading routines that will do that.

If you read the entire file as a character vector, and put '[' before and ']' after, and evalc() then possibly you would get what you are after.

... At least until someone puts

system('format C:\')

into an input file for the lulz.

Answer 1

[Walter Roberson]

Your Z column contains text but your other columns are numeric. It is not possible to create a single array that contains both text and numeric, other than converting to a cell array such as by using table2cell()

Note: when you assign values to variables, such as the way you assign to R1 and R2 here, and then you try to read from a file that contains text that matches variable names... then the values of the MATLAB variables will not be automatically substituted where the text occurs.

Also note that Excel has no way to represent complex numbers, so the 0.01+0.1j can only be read in as text.

[ubaidulla]

Thank you for your response. Here

"Also note that Excel has no way to represent complex numbers, so the 0.01+0.1j can only be read in as text."

For instance, if I change the contents of column Z in file "my_data.csv", as follows:

0.04+0.3j

0.04+0.4j

0.01+0.1j

0.02+0.2j

and then if I run the code

my_data_1  = readtable('my_data.csv')
my_data_2 = table2array(my_data_1(:,1:4));
Y=1./my_data_2(:,4)

then my result will be

Y =

0.43668 - 3.2751i

0.24752 - 2.4752i

0.9901 - 9.901i

0.49505 - 4.9505i

That means 'complex' data can be read from csv file.

My question is 'is it possible to use a variable name inside .CSV file and assign its value in matlab commandwindow?

Thank you

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/1738690-unable-to-concatenate-the-table-variables#comment_2211600