Why my regexp for hyphenated words doesn t work

Question

I m writting a regular expression for match with simple words and single hyphenated words using re module of python  so for example in   test case input      the wide-field infrared survey explorer is a nasa infrared-wavelength space telescope in an earth-orbiting satellite which performed an all-sky astronomical survey  be careful of -tricky tricky- hyphens --- be precise       should be match   test case output     the    wide-field    infrared    survey    explorer    is    a    nasa    infrared-wavelength    space    telescope    in    an    earth-orbiting    satellite    which    performed    an    all-sky    astronomical    survey    be    careful    of    tricky    tricky    hyphens    be    precise     I found a regular expression that match single hyphenated words  r  a-z  - a-z    and another for the simple words r  a-z    then I tried with an or r  a-z  - a-z      a-z    but the output is wrong      wide     infrared     survey     explorer     is     a     nasa     infrared-wavelength      telescope     in     an     earth     satellite      which     an     all     astronomical     survey     be     careful     of      tricky     be     precise     If I use gruops  r     a-z  - a-z          a-z     neither  and another solution that I think that shold be work r  a-z     - a-z      neither does   It is obviously possible  but there is something that I does not clearly understand  What s wrong

User · Answer

You can use this   r  a-z     - a-z

User · Answer

This regex should do it    b a-z  - a-z   b    b indicates a word-boundary

User · Answer

A couple of things    Your regexes need to be anchored by separators  or you ll match partial words  as is the case now You re not using the proper syntax for a non-capturing group  It s     not       If you address the first problem  you won t need groups at all    That is  a blank or beginning end of string

[python] Why my regexp for hyphenated words doesn't work?

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