MicroPython Forum (Archive)

If I run the
tmp=re.match('^abc(.*?)cde$','abc123213cde')
tmp.group(1)
it can print '123213'.
but if I run the
a=b'\r\nSEND OK\r\nAT+CIPSEND=125\r\n~011200g\x8a\xb0\xd3F\x0b\xc9\x88\x1e\x9d\xaf\x14\x9f\xfb\x9fR\xcb\xc5\xb4"\xf8>\xff\x0ftc t,\x18\xfa\xad\xf7!0V\xb6\xa6Y\xefH8\x0e\x17\xd4\xc8s\x0f\x04\xd5\xb9+\xbev\x8ej\x0b\xb8.Zf\xe0}\x01\x8f!y_%\xe9\xacO\xf64\xd3K\x06N\x99\xeeR\x92\x7fw7|\x90\x95r\xe8q\xbdnf\x137w=j\x85U\xc6\x93\xceb*\x8d\x96\xeaw\xa1\xee\xf8\r\n> \xd1\xae\xd4\x89~\r\nSEND OK\r\n~003200\xb5\xe6\x946\xcc\n\x11\x9d\xf0]\xd7i\x88\xdc}\x02<\xf1\xd5\x03\xe8\x0b\x14\xdaM\xb8G\x03F\x93\xd6\x8fg\x00\xfa\x86\x04~'
tmp=re.match('^~0(.*?)~$',a)
tmp.group(1)
it will return None, who can tell me why?

re.match() is anchored to the start of the string. You have to use re.search(), if the pattern is in the middle of the string. And in re.search(), '^' and '$' mean the begin and end of the string, not special characters like \r or \n.

Roberthh wrote:re.match() is anchored to the start of the string. You have to use re.search(), if the pattern is in the middle of the string. And in re.search(), '^' and '$' mean the begin and end of the string, not special characters like \r or \n.

the function match and search will get the same rezult. it can not work

wwsheldons wrote:who can tell me why?

Me. It is because your second regex tries to match '~0' at the beginning ('^') of the string, but the value of a doesn't match. If you want to match at the beginning of a line, you need the re.MULTILINE flag. Not sure if the micropython re module supports that.

https://docs.python.org/3/library/re.ht ... e-contents

SpotlightKid wrote:

wwsheldons wrote:who can tell me why?

Me. It is because your second regex tries to match '~0' at the beginning ('^') of the string, but the value of a doesn't match. If you want to match at the beginning of a line, you need the re.MULTILINE flag. Not sure if the micropython re module supports that.

https://docs.python.org/3/library/re.ht ... e-contents

tmp=re.match('^abc(.*?)cde$','abc123213cde')
can work well

Besides the problem of anchored and non-anchored search, there seems to be a problem with the data.
I tried to split up a in to lines and search/match these against the search pattern, with no success.
Using a text with only ASCII character works. So it may be related to what your searching at. Trying something like:
gets a match, but: does not. It does not matter whether search or match is used in that case. The problems are the null bytes in the string.
You may change the loop into: Then it works, but with a changed search object.

Roberthh wrote:Besides the problem of anchored and non-anchored search, there seems to be a problem with the data.
I tried to split up a in to lines and search/match these against the search pattern, with no success.
Using a text with only ASCII character works. So it may be related to what your searching at. Trying something like:

Code: Select all

a=b'\r\nSEND OK\r\nAT+CIPSEND=125\r\n~011200g\x8a\xb0\xd3F\x0b\xc9\x88\x1e\x9d\xaf\x14\x9f\xfb\x9fR\xcb\xc5\xb4"\xf8>\xff\x0ftc t,\x18\xfa\xad\xf7!0V\xb6\xa6Y\xefH8\x0e\x17\xd4\xc8s\x0f\x04\xd5\xb9+\xbev\x8ej\x0b\xb8.Zf\xe0}\x01\x8f!y_%\xe9\xacO\xf64\xd3K\x06N\x99\xeeR\x92\x7fw7|\x90\x95r\xe8q\xbdnf\x137w=j\x85U\xc6\x93\xceb*\x8d\x96\xeaw\xa1\xee\xf8\r\n> \xd1\xae\xd4\x89~\r\nSEND OK\r\n~003200\xb5\xe6\x946\xcc\n\x11\x9d\xf0]\xd7i\x88\xdc}\x02<\xf1\xd5\x03\xe8\x0b\x14\xdaM\xb8G\x03F\x93\xd6\x8fg\x00\xfa\x86\x04~'
for l in a.decode().split("\r"):
     tmp=re.search("~0", l.lstrip("\n"))

gets a match, but:

Code: Select all

tmp=re.search('~0(.*?)~', l.lstrip("\n"))

does not. It does not matter whether search or match is used in that case. The problems are the null bytes in the string.
You may change the loop into:

Code: Select all

for l in a.decode().split("\r"):
    ll = repr(l.lstrip("\n"))
    tmp=re.search('~0(.*?)~', ll)
    if tmp:
         print ("match", tmp.group(1))

Then it works, but with a changed search object.

thanks!