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Return a value from a table

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Ivan Glinski
Ivan Glinski on 29 Nov 2019
Commented: Ivan Glinski on 30 Nov 2019
Hello,
I have a table of annual quarters as row names and the dates those quarters began as a variable. I'm trying to create a command where given a quarter (R) I can lookup the quarter start date. I've read the documentation and searched for answers here, but am very lost so I'd appreciate any help!
Quarter = {'Q12019'; 'Q22019'; 'Q32019'; 'Q42019'; 'Q12020'; 'Q22020'; 'Q32020'; 'Q42020'};
QuarterStartDate = ['2019-01-01'; '2019-04-01'; '2019-07-01'; '2019-10-01'; '2020-01-01'; '2020-04-01'; '2020-07-01'; '2020-10-01'];
T = table(QuarterStartDate, 'RowNames', Quarter);
R = 'Q32019';
S = T(Quarter == 'R')
I was able to do something similar earlier that worked, but that was using numbers rather than characters. I tried doing the same thing, but that didn't work.
C = [ .80 ; .85 ; .90 ; .95];
P = [.55 ; .49 ; .44 ; .44];
T = table(C, P);
R = 0.95;
S = T{C == R, 2};
Thanks!

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Walter Roberson
Walter Roberson on 30 Nov 2019
S = T(strcmp(T.Quarter,'R').QuarterStartDate;
Ivan Glinski
Ivan Glinski on 30 Nov 2019
Thanks for your help!
After adding a parenthesis at the end to close the command around T, I get an error:
"Unrecognized variable name 'Quarter'."
Quarter is the row name, not a variable. If I change it so that Quarter is a variable in the table, I get the following error:
"Error: Functions cannot be indexed using {} or . indexing."
Image Analyst
Image Analyst on 30 Nov 2019
Try T.QuarterStartDate instead of T.Quarter.

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Accepted Answer

Stephan
Stephan on 30 Nov 2019
Edited: Stephan on 30 Nov 2019
Quarter = {'Q12019'; 'Q22019'; 'Q32019'; 'Q42019'; 'Q12020'; 'Q22020'; 'Q32020'; 'Q42020'};
QuarterStartDate = ['2019-01-01'; '2019-04-01'; '2019-07-01'; '2019-10-01'; '2020-01-01'; '2020-04-01'; '2020-07-01'; '2020-10-01'];
T = table(QuarterStartDate, 'RowNames', Quarter);
R = 'Q32019';
S = T(R,:)
results in:
S =
table
QuarterStartDate
________________
Q32019 2019-07-01
if you need only the content use curly braces:
S = T{R,:}
S =
'2019-07-01'

  1 Comment

Ivan Glinski
Ivan Glinski on 30 Nov 2019
It works, thank you!! I sort of can't believe the solution was this simple, but I'm still learning to think in Matlab terms.

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R2018b