Identifying the start of good data in a list

[tdmj]

I have a list that starts with zeros, has sporadic data, and then has
good data. I define the point at which the data turns good to be the
first index with a non-zero entry that is followed by at least 4
consecutive non-zero data items (i.e. a week's worth of non-zero data).
For example, if my list is [0, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9], I
would define the point at which data turns good to be 4 (1 followed by
2, 3, 4, 5).

...

With regular expressions:

Good grief. If you're suggesting that as a serious proposal, and not just
to prove it can be done, that's surely an example of "when all you have
is a hammer, everything looks like a nail" thinking.

In this particular case, your regex "solution" gives the wrong result,
indicating that you didn't test your code before posting. Hint:

re.search(r'[1-9]{5, }', "123456")

returns None.

The obvious fix for that specific bug is to use r'[1-9]{5,5}', but even
that will fail. Hint: what happens if an item has more than one digit?

Before posting another regex solution, make sure it does the right thing
with this:

[0, 0, 101, 0, 1002, 203, 3050, 4105, 5110, 623, 777]

Hey, it's clearer than a lot of the other proposals here. Too bad it
doesn't work. This is why you don't post after 8 p.m. after being at
work all day. I was seeing what I now recall as incorrect answers, but
at the time I was in the midst of a brainfart and for some reason took
them to be right. It can be made to work by removing the space in
"{5, }", inserting some kind of marker between the numbers, and using
the right regular expression to recognize nonzero numbers between the
markers, but I think I've already said too much in this thread.

Tommy McDaniel

 

[Jorgen Grahn]

I have a list that starts with zeros, has sporadic data, and then has
good data. I define the point at which the data turns good to be the
first index with a non-zero entry that is followed by at least 4
consecutive non-zero data items (i.e. a week's worth of non-zero data).
For example, if my list is [0, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9], I
would define the point at which data turns good to be 4 (1 followed by
2, 3, 4, 5).

...

With regular expressions:

Good grief. If you're suggesting that as a serious proposal, and not just
to prove it can be done, that's surely an example of "when all you have
is a hammer, everything looks like a nail" thinking.

Maybe I'm stumbling into a "REs are evil" flamewar here. Anyway:

He has a point though: this *can* be seen as a regex problem. Only a
solution which builds a string first is only good for laughs or
(possibly) quick hacks. What's missing is an RE library for lists of
objects, rather than just strings and Unicode strings.

Not sure such a library would be worth implementing -- problems like
this one are rare, I think.

/Jorgen

 

[castironpi]

On Aug 26, 5:49 pm, (e-mail address removed) wrote:
I have a list that starts with zeros, has sporadic data, and then has
good data. I define the point at  which the data turns good to be the
first index with a non-zero entry that is followed by at least 4
consecutive non-zero data items (i.e. a week's worth of non-zero data).
For example, if my list is [0, 0, 1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9], I
would define the point at which data turns good to be 4 (1 followed by
2, 3, 4, 5).

He has a point though: this *can* be seen as a regex problem. Only a
solution which builds a string first is only good for laughs or
(possibly) quick hacks. What's missing is an RE library for lists of
objects, rather than just strings and Unicode strings.

Not sure such a library would be worth implementing -- problems like
this one are rare, I think.

Every now and then, you see a proposal or a package for a finite state
machine--- how would you encode comparing of values into a string, if
you're not comparing a string?