I am trying to process covid-19 cases data
(the source, for interest: https://github.com/CSSEGISandData/COVID-19/blob/master/csse_covid_19_data/csse_covid_19_time_series/time_series_covid19_confirmed_global.csv)
The data forms a matrix, listing dates in columns and countries in rows. A simplified view:
country 1/20/20 1/21/20 1/22/20 ... etc. ...
China 100 120 144 ... etc. ...
US 0 0 1 ... etc. ...
...
etc.
...
I am trying to turn the date columns and the figures into two new features, say "date" and "confirmed", for as in:
country date confirmed
China 1/20/20 100
China 1/21/20 120
China 1/22/20 144
US 1/20/20 0
US 1/21/20 0
US 1/22/20 1
... etc. ...
I am interested in any solution that embeds in Orange, though - of course - we can prepare the data before importing it!
Are you trying to do it in a script or with canvas? With (pure) canvas, I guess you can't. You can of course always use a Python script widget and do it there.
In a script (standalone or within canvas) you should treat Orange.data.Table as immutable, although this is not enforced by Orange itself. A few versions back the obsolete methods that could change the number of rows were removed. You can still change the data in-place, but I wouldn't recommend it.
You will have to create a new table that will have the appropriate size from the start. I guess the simplest way to do it would be to collect all the data you need in a Python list (of lists) and then pass it to Table.from_list.
Disclosure: I'm one of Orange developers and I'm in the middle of writing a blog post using exactly this data. It's going to be a series and we would also show some scripts like this in a week or two.