大约有 44,100 项符合查询结果（耗时：0.0392秒） [XML]
How to determine equality for two JavaScript objects?
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How do you extract a column from a multi-dimensional array?
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Is there a NumPy function to return the first index of something in an array?
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edited Sep 12 '18 at 20:29
C. Braun
4,0501010 silver badges3737 bronze badges
answered Jan...
End of support for python 2.7?
Is there a known date/timeframe when python 2.7 will not be supported any more in favor of python 3?
9 Answers
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Delete an element from a dictionary
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1829
The del statement removes an element:
del d[key]
However, this mutates the existing dictiona...
How can I use Homebrew to install both Python 2 and 3 on Mac?
I need to be able to switch back and forth between Python 2 and 3. How do I do that using Homebrew as I don't want to mess with path and get into trouble.
Right now I have 2.7 installed through Homebrew.
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Check if two unordered lists are equal [duplicate]
...Counter(x) == collections.Counter(y)
>>>
>>> compare([1,2,3], [1,2,3,3])
False
>>> compare([1,2,3], [1,2,3])
True
>>> compare([1,2,3,3], [1,2,2,3])
False
>>>
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Can you supply arguments to the map(&:method) syntax in Ruby?
...h will enable you to do not only this:
a = [1,3,5,7,9]
a.map(&:+.with(2))
# => [3, 5, 7, 9, 11]
But also a lot of other cool stuff, like passing multiple parameters:
arr = ["abc", "babc", "great", "fruit"]
arr.map(&:center.with(20, '*'))
# => ["********abc*********", "********babc...
Convert column classes in data.table
...table’ and 'data.frame': 10 obs. of 3 variables:
$ ID : Factor w/ 2 levels "A","B": 1 1 1 1 1 2 2 2 2 2
$ Quarter: chr "1" "2" "3" "4" ...
$ value : num -0.838 0.146 -1.059 -1.197 0.282 ...
Using lapply and as.character:
dtnew <- dt[, lapply(.SD, as.character), by=ID]
str(dtnew...