How do you know if something is in an array or not in python?

Try using any:

any(1 in sub for sub in [[1,2,3],[4,5,6],[7,8,9]])

>>> list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
>>> any(1 in sub for sub in list)
True
>>> any(10 in sub for sub in list)
False
>>> any(7 in sub for sub in list)
True
>>> 

Well, if you know the contents of the list, you can use

if 1 in list[0]:
    do_something()
elif 1 in list[1]:
    do_something_else()
else: # 1 is in list[2]
    do_something_different()

Derived from "Dive Into Python"

list = [[1,2,3],[4,5,6],[7,8,9]]
if 1 in list[0]:

   do something

elif 1 in list[1]:

   do something

else:

   do something

...and so on. The in keyword takes a preceding value argument and returns a true if that value is in the proceeding list, false otherwise. The only other thing to know is list[0] accesses your first element in the top level list (the first sublist) and so on, allowing it to be searched for a specific integer using the in keyword.

Here's the expected output:

>>> list = [[1, 2, 3], [4, 5, 6], [7, 8, 9]]
>>> 1 in list[0]
True
>>> 1 in list[1]
False

To search all lists you can use the for keyword to loop over your lists and any to return true if any of the sublists match.

>>> any(1 in sublist for sublist in list)
True
>>> any(42 in sublist for sublist in list)
False

You can use Python's built-in "in" operator. This operator returns True if the item is in the iterable (list in this case), or False if it is not.

x_in_array = x in array

The Python doc that covers this is here, under section 5.6: https://docs.python.org/2/library/stdtypes.html

Your if/elif/else statements would then look like:

if x in array_1:
    # do something
elif x in array_2:
    # do something
else:
    # do something else

If you want to return the index of the list:

>>> def idx_check(i, l):
...     for (idx, val) in enumerate(l):
...         if i in val:
...             return idx
...     return None
...

>>> l = [[1,2,3],[4,5,6],[7,8,9]] 
>>> idx_check(1, l)
0
>>> idx_check(4, l)
1
>>> idx_check(7, l)
2

First of all: I know it's just an example, but don't use list as a variable in Python. It is a keyword/built-in function.

Second: you can use iteration to accomplish this. You can iterate through the members of a list (or any iterable object, or any iterator) like this:

for item in L:
    # do something with item

You can keep track of the number of times you have entered the loop using the enumerate function. The enumerate function returns a two-tuple in the form of member_index_number, member:

for num,item in enumerate(L):
    # do something with num and item

Almost there- now you need a way to associate the above iteration with your list of functions. The usual way this is done in python is with a dictionary, but you could also just use a list.

# list way
funcs_list = [f1, f2, f3]
for num,item in enumerate(L):
    if 1 in item:
        funcs_list[funcs_list.index(num)]()
        break

# dictionary way
funcs_dict = {0: f1, 1: f2, 2: f3}
for num,item in enumerate(L):
    if 1 in item:
        funcs_dict[num]()
        break

The dictionary method is usually preferred because it looks much cleaner.