You can use the str.split method.

>>> my_string = 'A,B,C,D,E'
>>> my_list = my_string.split(",")
>>> print my_list
['A', 'B', 'C', 'D', 'E']

If you want to convert it to a tuple, just

>>> print tuple(my_list)
('A', 'B', 'C', 'D', 'E')

If you are looking to append to a list, try this:

>>> my_list.append('F')
>>> print my_list
['A', 'B', 'C', 'D', 'E', 'F']

line.decode() returns a string (a str), not a list. So you are getting back a single entity, not 288 values.

Python has a method associated with strings that will take a string and split it into component parts. Calling the .split() method and giving it the substring to split upon, in this case a ',' should do the trick.

#Read the line of data from the sensor
line = sensor.readline()

#Decode the line to UTF-8 and print it
lineDecoded = line.decode("UTF-8")


values = [int(i) for i in lineDecoded.split(',')]    # <<< this should work
                                                     # added a list
                                                     # comprehension to 
                                                     # convert values to integers


x = range(1,289)                   # <<< this is preferred if you need 
                                   # a range of numbers from 1 to 288

y = values

#Plot the data
pg.plot(x, y)

NOTE: as @umutto mentions in a comment above, for plotting purposes, there should be no need to convert the values to a numpy array. A list should do just fine.

But, if for some reason you find that you want/need an array:

y = np.array(values)

One would 1st call the string's · split · method: · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .split(','); · gs.debug('\n[' + array.join(']\n[') + ']'); · This prints: · *** Script: [DEBUG] · [ item 1] · [ item 2 ] · [ ] · [item 3 ] · Pretty all over the place. · For better result - where the leading and trailing spaces are removed - one would use · trim · before splitting: · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .trim() · .split(','); · gs.debug('\n[' + array.join(']\n[') + ']'); · *** Script: [DEBUG] · [item 1] · [ item 2 ] · [ ] · [item 3] · Really only slightly better - only the 1st and the last items look good - and half of both only by chance (the one who entered the list did not add extra spaces after the last item and before the 1st one). · To take care of all extra spaces for all items that could exist due to sloppy fellow programmers composing the list or faulty data entry, one would switch the splitter to · RegExp · : · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .trim() · .split(/\s*,\s*/g); · gs.debug('\n[' + array.join(']\n[') + ']'); · *** Script: [DEBUG] · [item 1] · [item 2] · [] · [item 3] · A lot better, almost there, just one problem remains: the 3rd item which is empty. · To take care of that problem one might · filter · the resulting array: · var list = ' item 1, item 2 , ,item 3 '; · var array = list · .trim() · .split(/\s*,\s*/g) · .filter(retainNotEmpty); · function retainNotEmpty (item) { · return '' != item; · } · gs.debug('\n[' + array.join(']\n[') + ']');​ · *** Script: [DEBUG] · [item 1] · [item 2] · [item 3] · Just about what one desires. · Filtering will also fix the issue of empty string ending up (not in a 0 length array, but) in an array with one item when split.

location_in  = 'London, Greater London, England, United Kingdom'
locations    = location_in.split(', ')
location_out = [', '.join(locations[n:]) for n in range(len(locations))]

const array = str.split(',');

MDN reference, mostly helpful for the possibly unexpected behavior of the limit parameter. (Hint: "a,b,c".split(",", 2) comes out to ["a", "b"], not ["a", "b,c"].)