# How to define the number of the column in which a variable corresponds

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Ivan Mich on 23 Jan 2023
Commented: Image Analyst on 23 Jan 2023
I have a question about a code. I use the following command in order to read a file:
T=readtable('file.txt')
A=(T:,1);
B=(T:,2);
C=(T:,3);
which command should I use in order to define the number of the column in which a variable corresponds?
for example A coresponts to column 1 (so I want answer=1), B coresponts to column 1 (so I want answer=2), , etc.
Could you please help me?
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Ivan Mich on 23 Jan 2023
I would like to export the number 1 (that represents the number of specific column i T table) of command
A=(T:,1)
the number 2 of command
B=(T:,2)
the number 3 of command
C=(T:,3) etc...
Could you please help me?
Image Analyst on 23 Jan 2023
I did help you. Below in the official Answers section. Did you even see it?

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### Answers (1)

Image Analyst on 23 Jan 2023
As soon as you assign A, B, and C, you can also create a dictionary so that later in your code you can recall what column they came from
T = randi(9, 5, 3);
A = T(:, 1);
B = T(:, 2);
C = T(:, 3);
dict = dictionary(["A"; "B"; "C"], [1;2;3])
dict =
dictionary (stringdouble) with 3 entries: "A" ⟼ 1 "B" ⟼ 2 "C" ⟼ 3
% What column is A from
col = dict("A")
col = 1
% What column is B from
col = dict("B")
col = 2
% What column is C from
col = dict("C")
col = 3
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