List comprehension vs. lambda + filter

Question

I happened to find myself having a basic filtering need: I have a list and I have to filter it by an attribute of the items.

My code looked like this:

Answer 1

In addition to the accepted answer, there is a corner case when you should use filter instead of a list comprehension. If the list is unhashable you cannot directly process it with a list comprehension. A real world example is if you use pyodbc to read results from a database. The fetchAll() results from cursor is an unhashable list. In this situation, to directly manipulating on the returned results, filter should be used:

cursor.execute("SELECT * FROM TABLE1;")
data_from_db = cursor.fetchall()
processed_data = filter(lambda s: 'abc' in s.field1 or s.StartTime >= start_date_time, data_from_db) 

If you use list comprehension here you will get the error:

TypeError: unhashable type: 'list'