How to separate a Python list into two lists, according to some aspect of the elements

Question

I have a list like this:

[[8, \"Plot\", \"Sunday\"], [1, \"unPlot\", \"Monday\"], [12, \"Plot\", \"Monday\"], [10, \"Plot\", \"Tuesday\"], [4, \"unPlot\", \"         


        

Answer 1

Try with basic list comprehension:

>>> [ x for x in l if x[1] == "Plot" ]
[[8, 'Plot', 'Sunday'], [12, 'Plot', 'Monday'], [10, 'Plot', 'Tuesday'], [14, 'Plot', 'Wednesday'], [19, 'Plot', 'Thursday'], [28, 'Plot', 'Friday']]
>>> [ x for x in l if x[1] == "unPlot" ]
[[1, 'unPlot', 'Monday'], [4, 'unPlot', 'Tuesday'], [6, 'unPlot', 'Wednesday'], [1, 'unPlot', 'Thursday'], [10, 'unPlot', 'Friday'], [3, 'unPlot', 'Saturday']]

Or with filter if you fancy functional programming:

>>> filter(lambda x: x[1] == "Plot", l)
[[8, 'Plot', 'Sunday'], [12, 'Plot', 'Monday'], [10, 'Plot', 'Tuesday'], [14, 'Plot', 'Wednesday'], [19, 'Plot', 'Thursday'], [28, 'Plot', 'Friday']]
>>> filter(lambda x: x[1] == "unPlot", l)
[[1, 'unPlot', 'Monday'], [4, 'unPlot', 'Tuesday'], [6, 'unPlot', 'Wednesday'], [1, 'unPlot', 'Thursday'], [10, 'unPlot', 'Friday'], [3, 'unPlot', 'Saturday']]

I personally find list comprehensions much clearer. It's certainly the most "pythonic" way.

Answer 2

You could simply go through the list, and check if the value is "Plot" like this:

for i in List:
  if i[1]=="Plot":
    list1.append(i)
  else:
    list2.append(i)