Appending elements to a list based on condition

Question

I was trying to append few elements to a list list_accepted_outsidenestant. When i try to print the list list_accepted_outsidenestant, i get: list_accepted_outsidenestant- [([971, 977, 728, 740], set([728, 977, 971, 740]))]. The list is showing a list and set with same elements. Can anyone pointout the mistake i am doing? Because of this, i am getting an error: set_accepted_outsidenest_antlist = set(list_accepted_outsidenestant TypeError: unhashable type: 'list'

I have shown part of code only relevant to the current question.

def leo(tag_data):
 available_ants_outside = []
 ori = []
 for id, (x, y) in tag_data:
 available_ants_outside.append(id)
 if for_coordinates_outside_nest((x, y)) is True:
 ori.append(id)
 return ori
def virgo(tag_data):
 available_ants_inside = []
 list_insidenest_ant_id = []
 set_inside_nest_ant_id = set()
 for id, (x, y) in tag_data:
 available_ants_inside.append(id)
 if for_coordinates_inside_nest((x, y)) is True:
 list_insidenest_ant_id.append(id)
 set_inside_nest_ant_id = set(list_insidenest_ant_id)
 return list_insidenest_ant_id,set_inside_nest_ant_id
 def bambino(ori,list_insidenest_ant_id):
 list_accepted_outsidenestant = [] 
 set_accepted_outsidenest_antlist = set()
 set_accepted_insidenest_antlist = set()
 if len(list_accepted_outsidenestant) < num_accepted:
 if (len(ori) > 0) or (len(list_insidenest_ant_id) >0):
 list_accepted_outsidenestant.extend(ori[0:min(len(ori), 
 num_accepted-len(list_accepted_outsidenestant))])
 set_accepted_outsidenest_antlist = set(list_accepted_outsidenestant) 
 print "list_accepted_outsidenestant-" + str(list_accepted_outsidenestant)
 set_accepted_insidenest_antlist = set(list_insidenest_ant_id)
 return set_accepted_outsidenest_antlist,set_list_outsideant_id,set_accepted_insidenest_antlist

• philippd: This code is very hard to read. Please try and trace down where the problem is introduced and the behavior is different from what you expect.
• Chris: In other words, please create a minimal reproducible example to demonstrate your problem.
• mudaliyar: @ChristianDean What i want is list_accepted_outsidenestant = [971, 977, 728, 740]
• mudaliyar: @philippd . I am just trying to extend the elements to a list list_accepted_outsidenestant. What i expect is; list_accepted_outsidenestant = [971, 977, 728, 740]. What i am getting is list_accepted_outsidenestant- [([971, 977, 728, 740], set([728, 977, 971, 740]))]
• philippd: I am not going through your code and fix the problem for you. At some point you append a tuple of sets to a list. You have to simply find out where and then convert the sets to lists and use the list.extend method or the list.append method.

Answer 1

The problem is that you're appending a list to a list. You can either iterate over the list you want to add:

items_to_add = ori[0:min(len(ori), 
 num_accepted-len(list_accepted_outsidenestant))]
for item in items_to_add:
 list_accepted_outsidenestant.append(item)

Or add the lists:

list_accepted_outsidenestant = list_accepted_outsidenestant + ori[0:min(len(ori), num_accepted-len(list_accepted_outsidenestant))]

Or as bruno pointed out (even better), extend the list.

list_accepted_outsidenestant.extend(ori[0:min(len(ori), num_accepted-len(list_accepted_outsidenestant))])

• bruno desthuilliers: or use list.extend(other_list).
• Jan Zeiseweis: Did not know this. Thanks
• mudaliyar: @JanZeiseweis I modified the code as suggested using extent. But the problem still persists
• Jan Zeiseweis: Than your problem might be the ori list. Where do you create this. Did you try to print ori before adding it to your existing list?
• zondo: Python also has the += operator which, if not as efficient as .extend(), is nearly so. (It's a shortcut for list.__iadd__().

Answer 2

append function add whole into other array
extend function extend add array into previous array

In [1]: a = [1,2,3,4]
In [2]: b = [10,9,8,7,6]
In [3]: a.append(b)
In [4]: a
Out[4]: [1, 2, 3, 4, [10, 9, 8, 7, 6]]
In [5]: c = [1,2,3,4]
In [6]: c.extend(b)
In [7]: c
Out[7]: [1, 2, 3, 4, 10, 9, 8, 7, 6]

Hope this code help you

• mudaliyar: I understood what you mentioned. I tried to use extend instead of append, but still the problem persists
• Anurag Misra: can please explain what are trying in bit simpler way, because your code is very difficult to read.