3 ms·

> How many years old are you when you’re born? You have lived zero full years and are in the first year of your life. In most (but not all) countries the forme

by Ukv 2y ago

> How many years old are you when you’re born? You have lived zero full years and are in the first year of your life. In most (but not all) countries the former is considered "your age". That's consistent with both zero-based and one-based indexing. Both agree on cardinal numbers (an array [1, 2] has length 2), just not on ordinal numbers (whether the 1 in that array is the "first" or "zeroth" element). > I notice almost all defenses of 1-based indexing are purely based on arbitrary cultural factors or historical conventions, e.g. “that’s how it’s done in math”, rather than logical arguments. I think it's largely a matter of taste in either direction. But, I'd raise this challenge: arr = ['A', 'B', 'C', 'D', 'E', 'F'] slice = arr[3:1:-1] print(slice) If you're unfamiliar with Python (zero-based, half-open ranges exclusive of end), that's taking a slice from index 3 to index 1, backwards (step -1). How quickly can you intuit what it'll print? Personally I feel like I have to go through a few steps of reasoning to reach the right answer - even despite having almost exclusively used languages with 0-based indexing. If Python were instead to use MatLab-style indexing (one-based, inclusive ranges), I could immediately say ['C', 'B', 'A'].

School-Cotton 2y ago
I don’t know python but I figured out immediately that it should print ['C', 'B']. Does it? If not, Python is just wrong.
- pansa2 2y ago
  No, it doesn't, it prints ['D', 'C']. I agree that it should be ['C', 'B'] - the way that Python handles negative `step` values is wrong.
  - Ukv 2y ago
    I don't think it's "wrong" per se - it's zero-based indexing and ranges are consistently inclusive of start, exclusive of end. But, it breaks the "fence-post" mental model that some people use, and is less intuitive than MatLab's indexing approach IMO.
    - pansa2 2y ago
      > I don't think it's "wrong" per se I do. I think it only makes sense for ranges to be inclusive at the lower end and exclusive at the higher end. A slice with a negative step `-n` should contain the same elements as the same slice as with step `n`, just reversed.
weinzierl 2y ago
Both agree on cardinal numbers (an array [1, 2] has length 2), just not on ordinal numbers (whether the 1 in that array is the "first" or "zeroth" element). I think whenever people say "zeroth" they speak in jest and doubt that there is any disagreement on the fact that the element without predecessor (nowadays in programming most often assigned index 0) is the first element. You used "first" in that sense naturally just in the sentence before without the slightest notion of ambiguity. You have lived zero full years and are in the first year of your life. What people wrongly get riled up with is the fact that ordinal (first) is not in sync with the cardinal (index 0), but it rarely is anyways. If you go to an administrative office and pull your number 5357 no one assumes that there are 5356 people in the queue before them. Your are still the 5th or 10th in line, even if your index is 5357.
- Ukv 2y ago
  > I think whenever people say "zeroth" they speak in jest and doubt that there is any disagreement on the fact that the element without predecessor (nowadays in programming most often assigned index 0) is the first element. "Zeroth" sounds silly because English has generally settled on one-based indexing, and so typically you'd convert to one-based indexing when speaking out loud or writing something other than code (`users[3]` is the "4th user"). Maybe you could argue that the words "first"/"second", as just some letters/sounds, are not inherently one-based? But I feel that gets a bit dubious from "third" onwards where the connection to numbers is obvious, and with the ordinals frequently spelled as 1st/2nd/etc. But, if you want (and if I'm understanding what you mean), you could replace my statement with: "whether the '1' in that array is the index-1 or index-0 element" - purpose was just to distinguish between ordinals and cardinals, in response to a comment that seemingly implied the cardinality of an empty collection would be 1 with one-based-indexing.

by Ukv 2y ago

School-Cotton 2y ago

I don’t know python but I figured out immediately that it should print ['C', 'B']. Does it? If not, Python is just wrong.

pansa2 2y ago
No, it doesn't, it prints ['D', 'C']. I agree that it should be ['C', 'B'] - the way that Python handles negative `step` values is wrong.
- Ukv 2y ago
  I don't think it's "wrong" per se - it's zero-based indexing and ranges are consistently inclusive of start, exclusive of end. But, it breaks the "fence-post" mental model that some people use, and is less intuitive than MatLab's indexing approach IMO.
  - pansa2 2y ago
    > I don't think it's "wrong" per se I do. I think it only makes sense for ranges to be inclusive at the lower end and exclusive at the higher end. A slice with a negative step `-n` should contain the same elements as the same slice as with step `n`, just reversed.

weinzierl 2y ago

Both agree on cardinal numbers (an array [1, 2] has length 2), just not on ordinal numbers (whether the 1 in that array is the "first" or "zeroth" element). I think whenever people say "zeroth" they speak in jest and doubt that there is any disagreement on the fact that the element without predecessor (nowadays in programming most often assigned index 0) is the first element. You used "first" in that sense naturally just in the sentence before without the slightest notion of ambiguity. You have lived zero full years and are in the first year of your life. What people wrongly get riled up with is the fact that ordinal (first) is not in sync with the cardinal (index 0), but it rarely is anyways. If you go to an administrative office and pull your number 5357 no one assumes that there are 5356 people in the queue before them. Your are still the 5th or 10th in line, even if your index is 5357.

Ukv 2y ago
> I think whenever people say "zeroth" they speak in jest and doubt that there is any disagreement on the fact that the element without predecessor (nowadays in programming most often assigned index 0) is the first element. "Zeroth" sounds silly because English has generally settled on one-based indexing, and so typically you'd convert to one-based indexing when speaking out loud or writing something other than code (`users[3]` is the "4th user"). Maybe you could argue that the words "first"/"second", as just some letters/sounds, are not inherently one-based? But I feel that gets a bit dubious from "third" onwards where the connection to numbers is obvious, and with the ordinals frequently spelled as 1st/2nd/etc. But, if you want (and if I'm understanding what you mean), you could replace my statement with: "whether the '1' in that array is the index-1 or index-0 element" - purpose was just to distinguish between ordinals and cardinals, in response to a comment that seemingly implied the cardinality of an empty collection would be 1 with one-based-indexing.