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Understanding the map function
Apply function to every item of iterable and return a list of the results. If additional iterable arguments are passed, function must take that many arguments and is applied to the items from all iterables in parallel.
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How can I convert a dictionary into a list of tuples?
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>>> d = { 'a': 1, 'b': 2, 'c': 3 }
>>> d.items()
[('a', 1), ('c', 3), ('b', 2)]
>>> [(v, k) for k, v in d.iteritems()]
[(1, 'a'), (3, 'c'), (2, 'b')]
It's not in the order you want, but dicts don't have any specific order an...
Is it good practice to use the xor operator for boolean checks? [closed]
...ke the exclusive or , ^ , operator when it makes sense in the context of boolean checks because of its conciseness. I much prefer to write
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Covariance, Invariance and Contravariance explained in plain English?
Today, I read some articles about Covariance, Contravariance (and Invariance) in Java. I read the English and German Wikipedia article, and some other blog posts and articles from IBM.
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Shortcuts in Objective-C to concatenate NSStrings
Are there any shortcuts to ( stringByAppendingString: ) string concatenation in Objective-C, or shortcuts for working with NSString in general?
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Reference — What does this symbol mean in PHP?
This is a collection of questions that come up every now and then about syntax in PHP. This is also a Community Wiki, so everyone is invited to participate in maintaining this list.
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When is “i += x” different from “i = i + x” in Python?
...he standard notation of i = i + . Is there a case in which i += 1 would be different from i = i + 1 ?
3 Answers
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使用TokuMX配置Replica Set集群 - 大数据 & AI - 清泛网 - 专注C/C++及内核技术
使用TokuMX配置Replica Set集群MongoDB作为NoSql首选，使用较为广泛，但TokuMX鲜为人知，它完全兼容MongoDB，性能上较MongoDB更为出色，尤其其数据压缩及处理海量数据性能方面更是远远优于MongoDB。TokuTek公司出品的TokuDB，其主要特色是在...
Why avoid increment (“++”) and decrement (“--”) operators in JavaScript?
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My view is to always use ++ and -- by themselves on a single line, as in:
i++;
array[i] = foo;
instead of
array[++i] = foo;
Anything beyond that can be confusing to some programmers and is just not worth it in my view. For loops are an exception, as the...
How to check if PHP array is associative or sequential?
PHP treats all arrays as associative, so there aren't any built in functions. Can anyone recommend a fairly efficient way to check if an array contains only numeric keys?
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