Python convert list of tuples into single tuple

Question

Is there a way to convert a list of tuples into a single tuple? I have received a list of tuples from cursor.fetchall() but would like to make this into a single tuple:

curr_table_columns = cursor.fetchall()

For example:

[(u'w_id',), (u'w_name',), (u'w_street',)]

becomes

[(u'w_id', u'w_name', u'w_street')]

Answer 1

With itertools.chain , it's trivial. from itertools import chain and you can do either:

[tuple(chain.from_iterable(curr_table_columns))]

or:

[tuple(chain(*curr_table_columns))]

The former is preferred for long or unbounded iterable inputs (though don't wrap in tuple for unbounded!); for a small input (particularly one that's already a list or tuple ), the latter is slightly slower, but fine. Either one is going to be significantly faster than a genexpr and indexing for inputs of any size at all.

Answer 2

Try this:

a=[(u'w_id',), (u'w_name',), (u'w_street',)]

print [tuple([i[0] for i in a])]

Output:

[(u'w_id', u'w_name', u'w_street')]

Answer 3

Not efficient*, but it is simple:

>>> ts = [(u'w_id',), (u'w_name',), (u'w_street',)]
>>> sum(ts, ())
('w_id', 'w_name', 'w_street')

So, just wrap it in a list if you must:

>>> result = [sum(ts, ())]
>>> result
[('w_id', 'w_name', 'w_street')]

*Warning: scales quadratically. Some might be inclined to let is slide for joining some column names into a single container. Definitely don't try to process millions of tuples this way.

Use itertools solution for linear time.

Answer 4

This function can convert listWidgets item into single tuple and also convert multiple element of tuple into single element tuple : Used for Sqlite3 and data query from listwidgets.

def tuple_converter(self,item):
        target = ''
        for i in item:
            target += i + " " 
        target = target.rstrip()
        target = tuple(target.split(","))
        return target
#syntax  name = tuple_converter(tuple((item).split()))

'''