大约有 41,300 项符合查询结果（耗时：0.0474秒） [XML]
If list index exists, do X
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edited Dec 12 '16 at 0:03
Dimitris Fasarakis Hilliard
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How to implement a queue with three stacks?
...SUMMARY
O(1) algorithm is known for 6 stacks
O(1) algorithm is known for 3 stacks, but using lazy evaluation which in practice corresponds to having extra internal data structures, so it does not constitute a solution
People near Sedgewick have confirmed they are not aware of a 3-stack solution wi...
Impossible to Install PG gem on my mac with Mavericks
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253
If you want to avoid using MacPorts, you can download the Postgres App and place it into the App...
How to remove an element from a list by index
...y the index of the element you want to delete:
>>> a = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
>>> del a[-1]
>>> a
[0, 1, 2, 3, 4, 5, 6, 7, 8]
Also supports slices:
>>> del a[2:4]
>>> a
[0, 1, 4, 5, 6, 7, 8, 9]
Here is the section from the tutorial.
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C# short/long/int literal format?
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315
var d = 1.0d; // double
var d0 = 1.0; // double
var d1 = 1e+3; // double
var d2 = 1e-3; ...
Rails: Check output of path helper from console
... a Rails console, you can call app.post_path. This will work in Rails ~= 2.3 and >= 3.1.0.
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Get decimal portion of a number with JavaScript
I have float numbers like 3.2 and 1.6 .
22 Answers
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How do I replace NA values with zeros in an R dataframe?
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See my comment in @gsk3 answer. A simple example:
> m <- matrix(sample(c(NA, 1:10), 100, replace = TRUE), 10)
> d <- as.data.frame(m)
V1 V2 V3 V4 V5 V6 V7 V8 V9 V10
1 4 3 NA 3 7 6 6 10 6 5
2 9 8 9 5 10 NA 2 1 7 ...
Count number of records returned by group by
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13 Answers
13
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Some built-in to pad a list in python
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answered Aug 9 '10 at 9:43
John La RooyJohn La Rooy
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