大约有 43,500 项符合查询结果（耗时：0.0278秒） [XML]
Is there a NumPy function to return the first index of something in an array?
...
|
edited Sep 12 '18 at 20:29
C. Braun
4,0501010 silver badges3737 bronze badges
answered Jan...
Delete an element from a dictionary
...
1829
The del statement removes an element:
del d[key]
However, this mutates the existing dictiona...
How do you extract a column from a multi-dimensional array?
...
20 Answers
20
Active
...
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
...
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.
...
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
>>>
share
|
...
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...
How to calculate the angle between a line and the horizontal axis?
...lines extend infinitely and don't start at a particular point).
deltaY = P2_y - P1_y
deltaX = P2_x - P1_x
Then calculate the angle (which runs from the positive X axis at P1 to the positive Y axis at P1).
angleInDegrees = arctan(deltaY / deltaX) * 180 / PI
But arctan may not be ideal, because ...