Append the tabelename to a variable name in a table

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alpedhuez 2018-6-14

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评论： alpedhuez 2018-7-7

I have a table T. There are variables a,b,... in T. I would like to rename variables so that their names will be T_a,T_b,...etc. Please advise.

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Stephen23 2018-6-14

编辑：Stephen23 2018-6-14

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@alpedhuez: here is some pseudocode. Adjust to suit your situation:

S = dir(...)
T = readtable(S(1).name)
T.City = ... cityname: from filename ???
for k = 2:numel(S)
    U = readtable(S(k).name)
    U.City = ... cityname: from filename ???
    T = [T;U]
end

This is untested, it is just to illustrate one way to import multiple tables so that you do not need to magically access the table names, and can simply include the city name as a column in the table.

alpedhuez 2018-6-14

Let me work on it.

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回答（1 个）

Steven Lord 2018-6-14

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编辑：Steven Lord 2018-6-14

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Have a variable in the combined table named City. Rows in the combined table that came from your New York table would have NY in that variable, and those that came from your San Francisco table would have SF in that variable. Once you've added that variable to each of your tables, join them together using City as your key variable.

Once you have that as a variable in your table you could use it as the grouping variable in calls to groupsummary if you want to compute, say, the total population for all the regions / boroughs / etc. in your table that are in NY.

mytable = table({'NY'; 'SF'; 'NY'; 'NY'; 'SF'}, [1; 2; 3; 4; 5], ...
  'VariableNames', {'City', 'pop'})
totalPopulation = groupsummary(mytable, 'City', 'sum', 'pop')