Extract string with MID without specifying the number of characters

[Alisea_MI]

Hi,

I am new to Dax and I need to search for a text strings starting from the fourth character to the end of the string and if the text is there, return some other text. However, my string lengths differ, and when I am trying to use the MID function, I can't see how I can specify the number of characters to return since I don't know exactly where the string my text is. 

What I need to do is:

If string contains "ST" starting from the fourth character and to the end of the string, return "ST",

If string contains "LL", starting from the fourth character and to the end of the string, return "LL",

If string contains "X". staring from the forth character and to the end of the sring, return the last two characters of the string.

The expected outcome:

"SSDF RETEST Case NO.234" returns "ST"

"WF3 Stems" returns "ST",

"SW TF 6 X" returns "X"

Would really appreciate any help!

[AlexisOlson]

CONTAINSSTRING is useful here.

Column =
VAR Substring =
    RIGHT ( Table1[Column1], LEN ( Table1[Column1] ) - 4 )
RETURN
    SWITCH (
        TRUE (),
        CONTAINSSTRING ( Substring, "ST" ), "ST",
        CONTAINSSTRING ( Substring, "LL" ), "LL",
        CONTAINSSTRING ( Substring, "X" ), RIGHT ( Substring, 2 )
    )

[Alisea_MI]

@AlexisOlson Unfortunately this gives me an error for the variable. Do you know what problem can be? My column is a text type. 

[AlexisOlson]

Ah. You have some strings that are shorter than 4 characters.

The MID version of taking the substring is more robust to this issue.

[amitchandak · Accepted solution]

@Alisea_MI , Try a new column like

New column =
var _1 = mid([column],4 , len([column])
return
Switch(true(),
search("ST",_1,,0)>0, "ST",
search("LL",_1,,0)>0, "ST",
search("X",_1,,0)>0, right([column],2)
)