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What does the “yield” keyword do?
...ng its items one by one is called iteration:
>>> mylist = [1, 2, 3]
>>> for i in mylist:
... print(i)
1
2
3
mylist is an iterable. When you use a list comprehension, you create a list, and so an iterable:
>>> mylist = [x*x for x in range(3)]
>>> for i in my...
How to select rows with one or more nulls from a pandas DataFrame without listing columns explicitly
I have a dataframe with ~300K rows and ~40 columns.
I want to find out if any rows contain null values - and put these 'null'-rows into a separate dataframe so that I could explore them easily.
...
Array slices in C#
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13
Note using Array.Copy performs a lot faster than using LINQ's Take or Skip methods.
– Michael
Jun 23 ...
Converting int to bytes in Python 3
I was trying to build this bytes object in Python 3:
13 Answers
13
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NameError: global name 'xrange' is not defined in Python 3
...
You are trying to run a Python 2 codebase with Python 3. xrange() was renamed to range() in Python 3.
Run the game with Python 2 instead. Don't try to port it unless you know what you are doing, most likely there will be more problems beyond xrange() vs. range().
For the recor...
廉价共享存储解决方案1-drbd+ha+nfs - 更多技术 - 清泛网 - 专注C/C++及内核技术
...得无所适从而产生冲突。
另一种情况假如 tomact2,tomcat3同步tomcat1的目录，当tomcat1挂了之后，负载均衡会把访问分配到tomcat2和3，这个时候tomcat2和3彼此独立。客户分别对这两台机器进行读写于是数据又不同步了。
1.2 分布式...
How to create the most compact mapping n → isprime(n) up to a limit N?
...number with one bit e.g. for the given range of numbers (1, 10], starts at 3: 1110
31 Answers
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Import error: No module name urllib2
...on:
The urllib2 module has been split across several modules in Python 3 named urllib.request and urllib.error. The 2to3 tool will automatically adapt imports when converting your sources to Python 3.
So you should instead be saying
from urllib.request import urlopen
html = urlopen("http://ww...
Replace all 0 values to NA
...me space for it. E.g.,
data.frame(x = c(1, NA, 2))
# x
# 1 1
# 2 NA
# 3 2
Also, the data frame structure requires all the columns to have the same number of elements so that there can be no "holes" (i.e., NULL values).
Now you could replace zeroes by NULL in a data frame in the sense of com...
Using Python String Formatting with Lists
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edited Sep 27 '11 at 12:03
answered Sep 27 '11 at 11:53
in...