Best way to rename a loaded variable?

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Alec Nagel
Alec Nagel 2012-11-27
评论： Steven Lord 2022-3-17
Say that I have a .mat file that contains a variable, and I need to load this variable and give it a different name. Is there any other (/better) way to do this than:
load(myFile, myVar)
eval(['myNewname = ' myVar '; clear ' myVar])
?
  2 个评论
Jan
Jan 2012-11-27
Where does this EVAL idea come from? Did you find EVAL in the documentation or did you see it in an example?
I ask, because it is such frequently suggested to avoid EVAL in this and other Matlab forums for so many years, that I actually expect, that this method should be extinct already.
Alec Nagel
Alec Nagel 2012-11-27
True -- I have seen such admonitions too. They might have been what prompted the question, on some subconscious level :) The idea came from the top of my head, and/or someone's code I read. Matt's solution seems so obvious in hindsight, but I don't think I'm alone in not having thought of it and, somewhat guiltily, having resorted to EVAL instead.

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采纳的回答

Matt Fig
Matt Fig 2012-11-27
编辑：Matt Fig 2012-11-27
Say you have the name of your variable:
VAR = 'S';
Now you want to load that variable, but with the name T. This method follows the general rule of thumb to avoid 'poofing' variables into the workspace.
T = load('myfile',VAR); % Function output form of LOAD
T = T.(VAR)

更多回答（2 个）

Image Analyst
Image Analyst 2015-2-18
I'd do it this way:
storedStructure = load(myFile, 'myVar'); % Load in ONLY the myVar variable.
myNewname = storedStructure.myVar; % Assign it to a new variable with different name.
clear('storedStructure'); % If it's really not needed any longer.
Same net effect, it just uses the names Alec gave, and avoids dynamic structure fields, which are a bit advanced for beginners and not necessary here if you know the actual name.
Stefano Petrò
Stefano Petrò 2022-3-17
A way to do this in a single command is
myNewname = getfield(load(myFile,myVar),myVar);
  1 个评论
Steven Lord
Steven Lord 2022-3-17
Ran in:
If you're using release R2019b or later you can use dot indexing into the output of function calls.
myVar = 'cdate';
C = load('census.mat', myVar).(myVar)
C = 21×1
1790 1800 1810 1820 1830 1840 1850 1860 1870 1880

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