python - Dictionary Keys based on list elements and list values -

python - Dictionary Keys based on list elements and list values -

i scanning through document making list of each line read in.

i'm saving list called

testlist = []

when i'm done populating list want set value dictionary key based on element of list. thought should this:

testlist = ['informationa', 'informationb', 'lastinfo'] patent_offices = ['european office', 'japan office'] dict_offices[patent_offices[0]] = testlist

or

dict_offices = {'european office' : ['informationa', 'informationb', 'lastinfo'], 'japan office' : ['other list infoa', 'more infob']}

i want later type dict_offices['european office'] , list printed.

but because i'm collecting dynamically read through document erase , reuse testlist. i've seen after cleared cleared in dictionary's link.

how create dictionary saved can reuse testlist every loop through?

here code:

patent_offices = [] dict_offices = {} office_index = 0 testlist = [] # --- other conditional code not shown if (not patent_match , start_recording): if ( not re.search(r'[=]+', bstring)): #ignore ====== string printstring = fontsstring.encode('ascii', 'ignore') testlist.append(printstring) elif (not start_recording , patent_match): dict_offices[patent_offices[office_index]] = testlist start_recording = true office_index += 1 testlist[:] = []

this dictionary correctly updated , looks want until phone call

testlist[:] = []

line. dictionary goes blank testlist. understand dictionary linked don't know how not have happen.

lists mutable; multiple references same list see changes create it. testlist[:] = [] means: replace every index in list empty list. because reference same list in different places (including in dictionary values), see alter reflected everywhere.

instead, point testlist new empty list instead:

testlist = []

the empty piece assignment syntax used should used if want clear contents of list, not when want create new empty list.

>>> foo = [] >>> bar = foo >>> foo.append(1) >>> bar [1] >>> foo bar true >>> foo[:] = [] >>> bar [] >>> foo = ['new', 'list'] >>> bar [] >>> foo bar false

python list dictionary python-2.7