[@{$y_data{$cat}}] is a ref to a copy of the data for one $cat.

It is equivalent to [ $y_data{$cat}[0],$y_data{$cat}[1],$y_data{$cat}[2],etc ]

For a plot of all periods this would work equally as well

push @y_plotdata,$y_data{$cat};
poj

In reply to Re^5: Parsing an SQL table using an array of hashes? by poj
in thread Parsing an SQL table using an array of hashes? by chareTX

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