Select value from list of tuples where condition

Question

I have a list of tuples  Every tuple has 5 elements  corresponding to 5 database columns  and I d like to make a query  select attribute1 from mylist where attribute2   something   e g   personAge   select age from mylist where person id   10   Is it possible to query the list of tuples in some way

User · Accepted Answer

If you have named tuples you can do this:

results = [t.age for t in mylist if t.person_id == 10]

Otherwise use indexes:

results = [t[1] for t in mylist if t[0] == 10]

Or use tuple unpacking as per Nate's answer. Note that you don't have to give a meaningful name to every item you unpack. You can do (person_id, age, _, _, _, _) to unpack a six item tuple.

User · Answer

Yes  you can use filter if you know at which position in the tuple the desired column resides  If the case is that the id is the first element of the tuple then you can filter the list like so   filter lambda t  t 0   10  mylist    This will return the list of corresponding tuples  If you want the age  just pick the element you want  Instead of filter you could also use list comprehension and pick the element in the first go  You could even unpack it right away  if there is only one result     age     t 1  for t in mylist if t 0   10    But I would strongly recommend to use dictionaries or named tuples for this purpose

User · Answer

One solution to this would be a list comprehension  with pattern matching inside your tuple    gt  gt  gt  mylist     25 7   26 9   55 10    gt  gt  gt   age for  age person id  in mylist if person id    10   55    Another way would be using map and filter    gt  gt  gt  map  lambda  age     age  filter  lambda    person id   person id    10  mylist     55

[python] Select value from list of tuples where condition

Examples related to python

Examples related to list

Examples related to tuples