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Pandas read_csv low_memory and dtype options
...the last value.
Consider the example of one file which has a column called user_id.
It contains 10 million rows where the user_id is always numbers.
Since pandas cannot know it is only numbers, it will probably keep it as the original strings until it has read the whole file.
Specifying dtypes (shou...
Rails 3 migrations: Adding reference column?
... is kind of lost.
So I would do like this instead:
rails g migration add_user_id_to_tester user_id:integer
And then manually add belongs_to :user in the Tester model
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Separation of business logic and data access in django
...d each command is represented as a function.
services.py
def activate_user(user_id):
user = User.objects.get(pk=user_id)
# set active flag
user.active = True
user.save()
# mail user
send_mail(...)
# etc etc
Using forms
The other way is to use a Django Form for each co...
Does pandas iterrows have performance issues?
...ur problem. This is all vectorized.
In [58]: df = table1.merge(table2,on='letter')
In [59]: df['calc'] = df['number1']*df['number2']
In [60]: df
Out[60]:
letter number1 number2 calc
0 a 50 0.2 10
1 a 50 0.5 25
2 b -10 0.1 -1
3 b ...
What does preceding a string literal with “r” mean? [duplicate]
...slated. For example:
r'\n'
is a string with a backslash followed by the letter n. (Without the r it would be a newline.)
b does stand for byte-string and is used in Python 3, where strings are Unicode by default. In Python 2.x strings were byte-strings by default and you’d use u to indicate Un...
Difference between InvariantCulture and Ordinal string comparison
...end, it shows (excerpted):
StringComparison.InvariantCulture:
LATIN SMALL LETTER I (U+0069) is less than LATIN SMALL LETTER DOTLESS I (U+0131)
LATIN SMALL LETTER I (U+0069) is less than LATIN CAPITAL LETTER I (U+0049)
LATIN SMALL LETTER DOTLESS I (U+0131) is greater than LATIN CAPITAL LETTER I (U+0...
Rails: where does the infamous “current_user” come from?
...
It is defined by several gems, e.g. Devise
You'll need to store the user_id somewhere, usually in the session after logging in. It also assumes your app has and needs users, authentication, etc.
Typically, it's something like:
class ApplicationController < ActionController::Base
def cu...
What exactly do “u” and “r” string flags do, and what are raw string literals?
...a string literal consisting of only easily typable characters like english letters or numbers, you can simply type them: 'hello world'. But if you want to include also some more exotic characters, you'll have to use some workaround. One of the workarounds are Escape sequences. This way you can for e...
How do I execute a stored procedure once for each row returned by query?
... have a stored procedure that alters user data in a certain way. I pass it user_id and it does it's thing. I want to run a query on a table and then for each user_id I find run the stored procedure once on that user_id
...
An item with the same key has already been added
...erId { get; set; }
}
public class Model : BaseViewModel
{
public int User_Id { get; set; }
}
Now it is working fine.
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