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Reverse / invert a dictionary mapping
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For Python 2.7.x
inv_map = {v: k for k, v in my_map.iteritems()}
For Python 3+:
inv_map = {v: k for k, v in my_map.items()}
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How do I profile memory usage in Python?
I've recently become interested in algorithms and have begun exploring them by writing a naive implementation and then optimizing it in various ways.
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Check empty string in Swift?
In Objective C, one could do the following to check for strings:
14 Answers
14
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How do I read an attribute on a class at runtime?
I am trying to create a generic method that will read an attribute on a class and return that value at runtime. How do would I do this?
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jQuery.parseJSON throws “Invalid JSON” error due to escaped single quote in JSON
I’m making requests to my server using jQuery.post() and my server is returning JSON objects (like { "var": "value", ... } ). However, if any of the values contains a single quote (properly escaped like \' ), jQuery fails to parse an otherwise valid JSON string. Here’s an example of what I m...
How can I tell gcc not to inline a function?
Say I have this small function in a source file
8 Answers
8
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How to filter rows in pandas by regex
I would like to cleanly filter a dataframe using regex on one of the columns.
7 Answers
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Animation CSS3: display + opacity
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.parent:hover .child
{
display: block;
-webkit-animation: fadeInFromNone 0.5s ease-out;
-moz-animation: fadeInFromNone 0.5s ease-out;
-o-animation: fadeInFromNone 0.5s ease-out;
animation: fadeInFromNone 0.5s ease-out;
}
@-webkit-keyframes fadeInFromNone {
0% {
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Test whether string is a valid integer
I'm trying to do something common enough: Parse user input in a shell script. If the user provided a valid integer, the script does one thing, and if not valid, it does something else. Trouble is, I haven't found an easy (and reasonably elegant) way of doing this - I don't want to have to pick it ap...
Best way to merge two maps and sum the values of same key?
...al map1 = Map(1 -> 9 , 2 -> 20)
map1: scala.collection.immutable.Map[Int,Int] = Map(1 -> 9, 2 -> 20)
scala> val map2 = Map(1 -> 100, 3 -> 300)
map2: scala.collection.immutable.Map[Int,Int] = Map(1 -> 100, 3 -> 300)
scala> map1 |+| map2
res2: scala.collection.immutable...