help mata substr()
-------------------------------------------------------------------------------
Title
[M-5] substr() -- Extract substring
Syntax
string matrix substr(string matrix s, real matrix b, real matrix l)
string matrix substr(string matrix s, real matrix b)
Description
substr(s, b, l) returns the substring of s starting at position b and
continuing for a length of l, where
1. b specifies the starting position; the first character of the
string is b=1.
2. b>0 is interpreted as distance from the start of the string; b=2
means starting at the second character.
3. b<0 is interpreted as distance from the end of string; b = -1
means starting at the last character; b = -2 means starting at
the second from the last character.
4. l specifies the length; l=2 means for two characters.
5. l<0 is treated the same as l=0: no characters are copied.
6. l>=. is interpreted to mean to the end of the string.
substr(s, b) is equivalent to substr(s, b, .) for strings that do not
contain binary 0. If there is a binary 0 to the right of b, the
substring from b up to but not including the binary 0 is returned.
When arguments are not scalar, substr() returns element-by-element
results.
Conformability
substr(s, b, l):
s: r1 x c1
b: r2 x c2
l: r3 x c3; s, b, and l r-conformable
result: max(r1,r2,r3) x max(c1,c2,c3)
substr(s, b):
s: r1 x c1
b: r2 x c2; s and b r-conformable
result: max(r1,r2) x max(c1,c2)
Diagnostics
In substr(s, b, l) and substr(s, b), if b describes a position before the
beginning of the string or after the end, "" is returned. If b+l
describes a position to the right of the end of the string, results are
as if a smaller value for l were specified.
Source code
Function is built in.
Also see
Manual: [M-5] substr()
Help: [M-4] string
