I'm trying to use the "match" function and having a very ridiculous problem. If there is no match, the function returns error. Works fine if there is a match. This makes it useless. As best I can tell from the documentation the return should be "-1" if there is no match. What obvious thing am I missing?
Please point me to the location where it says that upon no match the function returns -1.
As far as I know, the reaction upon no match has always been an error.
Note that -1 is not a logic indication for no match, because you could set ORIGIN:=-1, which might mean that returning -1 the value was found at the first position. On the other hand, returning any (scalar) value should mean there's something wrong, because match is supposed to return a vector with the indices/positions (as you can see in the first example); but NaN could be another choice. However it was chosen to return an error in such cases.
If you want to get -1 upon no match, you'll have to write your own match() function, or embed it in a program where you trap the error:
Success!
Luc
@MR_10595556 wrote:
I'm trying to use the "match" function and having a very ridiculous problem. If there is no match, the function returns error.
You may not like this behaviour and may think that different one would be more appropriate, but I won't call this ridiculous.
This makes it useless.
I disagree, Would you also say the the implemented division operator is "useless" just because it throws an error when trying to divide b zero?
Error trapping is up to the user.
As best I can tell from the documentation the return should be "-1" if there is no match.
No! This is not the case and never was. Maybe you confuse the "match" function for vectors and matrices with the "search" function for strings!?
As Luc already suggested you may redefine the match function to return something meaningful if no match is found. That way you may have more control to react accordingly.
In Prime it may look like this:
Personally I would prefer a NaN as return value if no match was found.
Note that the built-in "match" function has an optional third argument -> Lookup Functions
When you type "match" your (re)defined function is used and it will throw an error if third argument is used.
You still can use the built-in function if you label the word "match" as being "Function":
Note the different typeface.
Of course you could also redefine the match function with the third argument:
So whenever you need the match function with its third argument, use the capital M, otherwise the lower case.
You may hide the redefinition of the functions at the top of the sheet - either in a collapsed region or in the non-printable area to the right of the right margin.
