大约有 45,000 项符合查询结果（耗时：0.0357秒） [XML]
How assignment works with Python list slice?
...two distinct operation that use very similar syntax:
1) slicing:
b = a[0:2]
This makes a copy of the slice of a and assigns it to b.
2) slice assignment:
a[0:2] = b
This replaces the slice of a with the contents of b.
Although the syntax is similar (I imagine by design!), these are two diff...
How to write the Fibonacci Sequence?
...urning the Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 should = only those numbers between 1 & 20), I have written for the program to display all Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 displays = First 20 Fibonacci numbers). I thought I had a sure-f...
Sorting arrays in NumPy by column
...ck example, to sort it and return a copy:
In [1]: import numpy as np
In [2]: a = np.array([[1,2,3],[4,5,6],[0,0,1]])
In [3]: np.sort(a.view('i8,i8,i8'), order=['f1'], axis=0).view(np.int)
Out[3]:
array([[0, 0, 1],
[1, 2, 3],
[4, 5, 6]])
To sort it in-place:
In [6]: a.view('i8,i8...
How to make lists contain only distinct element in Python? [duplicate]
...
278
The simplest is to convert to a set then back to a list:
my_list = list(set(my_list))
One d...
how to check the dtype of a column in python pandas
...
127
You can access the data-type of a column with dtype:
for y in agg.columns:
if(agg[y].dtype...
What do all of Scala's symbolic operators mean?
...to look for them. Or, failing that, look at the index (presently broken on 2.9.1, but available on nightly).
Every Scala code has three automatic imports:
// Not necessarily in this order
import _root_.java.lang._ // _root_ denotes an absolute path
import _root_.scala._
import _root_.scala.Pr...
Centering the pagination in bootstrap
...t;
<li><a href="?p=1" data-original-title="" title="">2</a></li>
</ul>
</div>
Bootstrap 4 has new class
<div class="text-xs-center">
<ul class="pagination">
<li><a href="?p=0" data-original-title="" title="">1&l...
Weighted random numbers
...e items have individual weights:
1) calculate the sum of all the weights
2) pick a random number that is 0 or greater and is less than the sum of the weights
3) go through the items one at a time, subtracting their weight from your random number, until you get the item where the random number is ...
How to create an object for a Django model with a many to many field?
...
248
You cannot create m2m relations from unsaved objects. If you have the pks, try this:
sample_o...