Sorting list of lists with string and int - Printable Version +- Python Forum (https://python-forum.io) +-- Forum: Python Coding (https://python-forum.io/forum-7.html) +--- Forum: General Coding Help (https://python-forum.io/forum-8.html) +--- Thread: Sorting list of lists with string and int (/thread-9943.html) |
Sorting list of lists with string and int - Otbredbaron - May-06-2018 So I'm trying to solve this exercise: https://open.kattis.com/problems/cups Although the problem is simple and does not require much work I'd like to improve my code because it looks pretty bad: #!/usr/bin/python3 n = int(input()) a = [input().split() for i in range(n)] for i in a: if(i[0].isdigit()): i[0] = int(i[0])/2 i[1], i[0] = i[0], i[1] elif(i[1].isdigit()): i[1] = int(i[1]) a.sort(key=lambda x: x[1]) [print(i[0]) for i in a]The main concern is that I don't know if the string will be in a form int string or string int so I need to check for it. RE: Sorting list of lists with string and int - Gribouillis - May-06-2018 You could use for i in a: try: i[1] = int(i[1]) except ValueError: i[0], i[1] = i[1], int(i[0]) / 2 RE: Sorting list of lists with string and int - Otbredbaron - May-06-2018 Why do we need to be explicit and write except ValueError? RE: Sorting list of lists with string and int - Gribouillis - May-06-2018 (May-06-2018, 11:42 AM)Otbredbaron Wrote: Why do we need to be explicit and write except ValueError?I'm not sure I understand exactly what you mean, but here I know that if i[1] contains anything that is not convertible to an integer the call to int() will raise ValueError. In such a case, I always catch the exact exception because I don't want to catch anything else. For example if for some reason there is no i[1] , python will throw KeyError and I don't want to catch this at this point. For debugging purposes, it is always better to let unexpected exceptions propagate.
RE: Sorting list of lists with string and int - buran - May-07-2018 actually, the easiest way would be to add sorted to your line 5 list comprehension a = [sorted(input().split()) for i in range(n)]this way you always get the number as element with index 0 because when sorting '0' to '9' always go before 'A' def parse_data(item): return (int(item[0]), item[1]) data = ['red 10', '10 blue', 'green 7'] data = [parse_data(sorted(item.split())) for item in data] output = [cup for radius, cup in sorted(data)] print('\n'.join(output))note that sample output in your assignment is NOT correct RE: Sorting list of lists with string and int - Otbredbaron - May-07-2018 (May-07-2018, 05:38 AM)buran Wrote: actually, the easiest way would be to add sorted to your line 5 list comprehension It is correct because if it's in the format number color, then number need to be divided by 2 so it will be 5. (May-06-2018, 02:26 PM)Gribouillis Wrote:(May-06-2018, 11:42 AM)Otbredbaron Wrote: Why do we need to be explicit and write except ValueError?I'm not sure I understand exactly what you mean, but here I know that if I see now, I need to get used to this try except thing. RE: Sorting list of lists with string and int - buran - May-07-2018 (May-07-2018, 05:54 AM)Otbredbaron Wrote: if it's in the format number color, then number need to be divided by 2 so it will be 5.sorry, didn't notice that - my mistake def parse_data(item): try: return int(item[0])/2, item[1] except ValueError: return (int(item[1]), item[0]) data = ['red 10', '10 blue', 'green 7'] data = [parse_data(item.split()) for item in data] output = sorted([cup for radius, cup in data]) print('\n'.join(output))and if you are comfortable with def parse_data(item): item = item.split() try: return int(item[0])/2, item[1] except ValueError: return (int(item[1]), item[0]) data = ['red 10', '10 blue', 'green 7'] print('\n'.join(sorted([cup for radius, cup in map(parse_data, data)]))) |