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Studies on optimal code width?
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Actually, the 80-column thing long precedes DOS. It comes from card punches, which were 80-column devices.
And to kind of answer the OP's question, one "study" has been going on for about 600 years now - the printed book. These have evolved over the centuries, with readbility forem...
Is there a library function for Root mean square error (RMSE) in python?
..._error function. The RMSE is just the square root of whatever it returns.
from sklearn.metrics import mean_squared_error
from math import sqrt
rms = sqrt(mean_squared_error(y_actual, y_predicted))
share
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Subqueries vs joins
I refactored a slow section of an application we inherited from another company to use an inner join instead of a subquery like:
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Adding :default => true to boolean in existing Rails column
...m not sure when this was written, but currently to add or remove a default from a column in a migration, you can use the following:
change_column_null :products, :name, false
Rails 5:
change_column_default :products, :approved, from: true, to: false
http://edgeguides.rubyonrails.org/active_rec...
Ioc/DI - Why do I have to reference all layers/assemblies in application's entry point?
... K and Library N. This makes it harder to reuse each library independently from the rest - for example in unit testing.
However, in a loosely coupled application, by moving all the references to the Composition Root, the dependency graph is severely flattened:
As illustrated by the green color, ...
Using global variables in a function
... to that function unless explicitly told otherwise. If it is only reading from a name, and the name doesn't exist locally, it will try to look up the name in any containing scopes (e.g. the module's global scope).
When you assign 42 to the name myGlobal, therefore, Python creates a local variable ...
Get file name from URL
In Java, given a java.net.URL or a String in the form of http://www.example.com/some/path/to/a/file.xml , what is the easiest way to get the file name, minus the extension? So, in this example, I'm looking for something that returns "file" .
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How do I convert datetime to ISO 8601 in PHP
How do I convert my time from 2010-12-30 23:21:46 to ISO 8601 date format? (-_-;)
6 Answers
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How do you delete a column by name in data.table?
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Any of the following will remove column foo from the data.table df3:
# Method 1 (and preferred as it takes 0.00s even on a 20GB data.table)
df3[,foo:=NULL]
df3[, c("foo","bar"):=NULL] # remove two columns
myVar = "foo"
df3[, (myVar):=NULL] # lookup myVar contents...
JSTL in JSF2 Facelets… makes sense?
...l UI components and they are executed during view render time.
Note that from JSF's own <f:xxx> and <ui:xxx> tags only those which do not extend from UIComponent are also taghandlers, e.g. <f:validator>, <ui:include>, <ui:define>, etc. The ones which extend from UICom...