python - Writing files only once -


i have scenario this:

a = ["file1","file2","file3","file1","file2","file1","file5"] set_flag = 0 in range (len(a)):     file_name = '%s.txt' %(a[i])     file_write = open('%s'%(file_name),'w')

the above works , writes files. however,i want include logic such though file names appear more once in above list file_write should happen once. there should not multiple file writes. e.g. if file1 appears 4 times should written once. set_flag should set "1" if try writing file1 anywhere in code should should bypass file write.any ideas how accomplish , set such flag..?

use set(), stores single copy of item:

>>> a=["file1","file2","file3","file1","file2","file1","file5"] >>> set(a) set(['file3', 'file2', 'file1', 'file5'])

for code, maintain order well.:

a=["file1","file2","file3","file1","file2","file1","file5"] seen=set() file in a:               #you can iterate on list     if file not in seen:     #if file not in set write         file_name= '%s.txt' %(file)        file_write= open('%s'%(file_name),'w')        seen.add(file)  #add file seen

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