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What is the most efficient way to create a dictionary of two pandas Dataframe columns?
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In [9]: pd.Series(df.Letter.values,index=df.Position).to_dict()
Out[9]: {1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'e'}
Speed comparion (using Wouter's method)
In [6]: df = pd.DataFrame(randint(0,10,10000).reshape(5000,2),columns=list('AB'))
In [7]: %timeit dict(...
Fastest check if row exists in PostgreSQL
...1 I have strong performance drop because Postgres uses Seq Scan instead of Index Scan. And analyze doesn't help.
– FiftiN
Jul 7 '16 at 10:41
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Manually map column names with class properties
...required sometime after version 1.13 of dapper
public ConstructorInfo FindExplicitConstructor()
{
return _mappers
.Select(mapper => mapper.FindExplicitConstructor())
.FirstOrDefault(result => result != null);
}
}
And with that in place, it becomes ...
Convert pandas timezone-aware DateTimeIndex to naive timestamp, but in certain timezone
You can use the function tz_localize to make a Timestamp or DateTimeIndex timezone aware, but how can you do the opposite: how can you convert a timezone aware Timestamp to a naive one, while preserving its timezone?
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How do you rename a MongoDB database?
...space (e.g.: dbName.collection) that describes every single collection and index includes the database name, so to rename a set of database files, every single namespace string would have to be rewritten. This impacts:
the .ns file
every single numbered file for the collection
the namesp...
Best way to randomize an array with .NET
...ursive step) shuffle the first n-1 elements of the array
choose a random index, x, in the range [0..n-1]
swap the element at index n-1 with the element at index x
The iterative equivalent is to walk an iterator through the array, swapping with random elements as you go along, but notice tha...
Pass props to parent component in React.js
...) {
var children = this.state.childrenData.map(function(childData,childIndex) {
return <Child onClick={this.handleChildClick.bind(null,childData)} text={childData.childText}/>;
}.bind(this));
return <div>{children}</div>;
},
handleChildClick: function(child...
How Drupal works? [closed]
...ed on slideshare, but a quick high-level summary may be useful.
Drupal's index.php file functions as a frontside controller. All page are piped through it, and the "actual" url/path the user requested is passed to index.php as a parameter.
Drupal's path router system (MenuAPI) is used to match the...
What are the main performance differences between varchar and nvarchar SQL Server data types?
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What about index size, memory usage etc? I assume you always use int when you could use tinyint too "just in case"?
– gbn
Jul 9 '10 at 7:02
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How to make CSS3 rounded corners hide overflow in Chrome/Opera
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Add a z-index to your border-radius'd item, and it will mask the things inside of it.
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