problem with 'extract' function

I am trying to extract characters from a string at a specific position using the 'extract' function.

However, even when entering the example code into my matlab program I get the error

Undefined function 'extract' for input arguments of type 'string'.

Can somebody help with this?

Matlab help page:

https://au.mathworks.com/help/matlab/ref/extract.html?s_tid=srchtitle

Section: Extract Character at Numeric Position

Create a string.

str = "All's well that ends well"

Extract the first character in the string.

extract(str,1)

From the command window:

>> str = "All's well that ends well"

str =

"All's well that ends well"

>> extract(str,1)

Undefined function 'extract' for input arguments of type 'string'.

Thanks!

Answer 1

[Star Strider]

The extract function was introduced in R2020b. If you have an earlier version/release, you need to upgrade to be able to use it. If you have R2020b and are still unable to use extract, run these commands:

restoredefaultpath 
rehash toolboxcache 

from a script or your Command Window and then try running it again. If you are still having problems after that, Contact Support.

[Damian Maxwell]

Thank you so much!

[Damian Maxwell]

I'll try to upgrade from my 2019 version

Answer 2

[dpb]

What do you get when you type

ver

at command line?

extract wasn't introduced until just now in R2020b so if you have a release earlier than that, you'll either have to upgrade or use the {} notation to get to the underlying char() string inside the string class string...

>> str = "All's well that ends well"
Extract the first character in the string.
extract(str,1)
str = 
    "All's well that ends well"
Unrecognized function or variable 'Extract'. 
>> str{:}(1)
ans =
    'A'
>> 

[Damian Maxwell]

Thanks DB. Your alternative method works.

[dpb]

That was the only way to extract a substring from a string variable prior to R2020b that released extract into the wild.