Is there a function like string2double that can handle a numerical input?

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Connor Brackley
Connor Brackley 2019-1-21
评论： Connor Brackley 2019-1-24
Hi!
I am importing data that sometimes imports as a string, and sometimes as a number. In all cases I want a number. Is there a function like string2double that can handle a numerical input?
Right now it works like:
>> str2num('2')
ans =
2
>> str2num(2)
Error using str2num (line 35)
Input must be a character vector or string scalar.
Ideally it would work like:
>> FunctionLikestr2num('2')
ans =
2
>> FunctionLikestr2num(2)
ans =
2
Thank you!

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采纳的回答

Steven Lord
Steven Lord 2019-1-21
First test if the input isnumeric. If it's not, try converting it from text data to a number.
  2 个评论
Stephen23
Stephen23 2019-1-22
编辑：Stephen23 2019-1-22
+1 a much more efficient solution.
The multiple type conversions used in the accepted answer are not necessary, and likely lose data precision and slow down the code. This is a much better answer: it makes it clear what the intent is.
Connor Brackley
Connor Brackley 2019-1-24
In the end I used the answer Luna submitted, but I'll flag this as the accepted answer as the loss of data is a concern.

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更多回答（1 个）

Luna
Luna 2019-1-21
You can do it first convert to string then convert to numeric:
str2num(string(2))
str2num(string('2'))
Both gives you numeric 2.
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显示 3更早的评论
Stephen23
Stephen23 2019-1-22
编辑：Stephen23 2019-1-22
@Luna: unfortunately str2num hides an eval call inside itself, which is why experienced MATLAB users try to avoid using it (especially inside loops). That is why str2double is recommended. The documentation states: "str2double Similar to str2num, but offers better performance and works with string arrays and cell arrays of character vectors."
source: https://www.mathworks.com/help/matlab/matlab_prog/converting-from-string-to-numeric.html

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