Given a symbol, how to check whether it has a particular prefix?
I had below code. It checks if a symbol begins with aaaaa but returns 1b for aaa which is wrong. I can add a length check but that seems verbose. Is there a cleaner way?
{"aaaaa"~-5#string x}[`$"aaa"]
It seems like the issue is with "take" since "aaa" is shorter than 5. It's extending "aaa" by 2/3 of itself in order to meet that length.
You could modify your function so you have the following:
q){"aaaaa"~(x) til 5}["aaa"]
0b
q){"aaaaa"~(x) til 5}["aaaaaaaa"]
1b
Expanding on Matthew's answer if you want to make a function out of it do the following:
q)f:{x like "aaaaa*"}
q)f[`aaa]
0b
q)f[`aaaaa]
1b
q)f[`aaaaabcde]
1b
And if you want to make it more dynamic you could add a second variable for the matching prefix.
q)f2[`aaa;"aaa"]
1b
q)f2:{x like y,"*"}
q)f2[`aaa;"aaaaa"]
0b
q)f2[`aaa;"aaa"]
1b
Let me know if you see any issues.