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How to store a dataframe using Pandas
...and read_pickle respectively).
Another popular choice is to use HDF5 (pytables) which offers very fast access times for large datasets:
store = HDFStore('store.h5')
store['df'] = df # save it
store['df'] # load it
More advanced strategies are discussed in the cookbook.
Since 0.13 there's...
What is the most efficient way to store a list in the Django models?
...be better expressed as a one-to-many foreign key relationship to a Friends table? I understand that myFriends are just strings but I would think that a better design would be to create a Friend model and have MyClass contain a foreign key realtionship to the resulting table.
...
NSLog the method name with Objective-C in iPhone
...t because the Objective-C runtime is dynamic, it's actually using a lookup table to figure out which method on which class to call so a char* is convenient since methods are represented as strings in the lookup table.
– Jack Lawrence
Nov 7 '12 at 16:42
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Why should C++ programmers minimize use of 'new'?
...omposes. It scales.
If you use the Line class as a building block:
class Table
{
Line borders[4];
};
Then
int main ()
{
Table table;
}
allocates four std::string instances, four Line instances, one Table instance and all the string's contents and everything is freed automagically...
How to read data when some numbers contain commas as thousand separator?
...
You can have read.table or read.csv do this conversion for you semi-automatically. First create a new class definition, then create a conversion function and set it as an "as" method using the setAs function like so:
setClass("num.with.commas...
MYSQL OR vs IN performance
...s the same.
$t = microtime(true);
for($i=0; $i<10000; $i++):
$q = DB::table('users')->where('id',1)
->orWhere('id',2)
->orWhere('id',3)
->orWhere('id',4)
->orWhere('id',5)
->orWhere('id',6)
->orWhere('id',7)
->orWhere('id',8)
->orWhere(...
How to find the statistical mode?
... hope it's helpful. It is also what I was thinking anyways. You'll want to table() the data, sort and then pick the first name. It's hackish but should work.
names(sort(-table(x)))[1]
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Why should I capitalize my SQL keywords? [duplicate]
...nk the latter is more readable. You can easily separate the keywords from table and column names, etc.
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How can I get a list of all functions stored in the database of a particular schema in PostgreSQL?
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After some searching, I was able to find the information_schema.routines table and the information_schema.parameters tables. Using those, one can construct a query for this purpose. LEFT JOIN, instead of JOIN, is necessary to retrieve functions without parameters.
SELECT routines.routine_name, pa...
How to implement a unique index on two columns in rails
I have a table and I'm trying to add a unique index on two columns. Those columns are also indexed. So my question is if I just can remove the indexes who were just for one column or if I have to use all three indexes:
...