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How is the undo tree used in Vim?
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See also :h undo-redo, which lists all the commands and their usage.
There are two ways to traverse the undo tree. One is to go "back in time". g+ and g- will traverse all of the nodes in the tree in chronological or reverse-chronological order (which can...
What does character set and collation mean exactly?
...a symbol, the number 0 is the
encoding for 'A', and the combination
of all four letters and their
encodings is a character set.
Now, suppose that we want to compare
two string values, 'A' and 'B'. The
simplest way to do this is to look at
the encodings: 0 for 'A' and 1 for
'B'. Be...
How to apply a function to two columns of Pandas dataframe
Suppose I have a df which has columns of 'ID', 'col_1', 'col_2' . And I define a function :
12 Answers
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Count how many records are in a CSV Python?
...aranteed to be a fixed size, so the only way to count them is to read them all.
– Martijn Pieters♦
Apr 19 '13 at 15:55
1
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Longest line in a file
...ing for a simple way to find the length of the longest line in a file. Ideally, it would be a simple bash shell command instead of a script.
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How to use clock() in C++
How do I call clock() in C++ ?
7 Answers
7
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Build Eclipse Java Project from Command Line
...ore.aptBuild
It uses the jdt apt plugin to build your workspace automatically. This is also known as a 'Headless Build'. Damn hard to figure out. If you're not using a win32 exe, you can try this:
java -cp startup.jar -noSplash -data "D:\Source\MyProject\workspace" -application org.eclipse.jdt....
Adding :default => true to boolean in existing Rails column
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change_column is a method of ActiveRecord::Migration, so you can't call it like that in the console.
If you want to add a default value for this column, create a new migration:
rails g migration add_default_value_to_show_attribute
Then in the migration created:
# That's the more generic way t...
Python dictionary: Get list of values for list of keys
...n list-comp:
Build list and throw exception if key not found: map(mydict.__getitem__, mykeys)
Build list with None if key not found: map(mydict.get, mykeys)
Alternatively, using operator.itemgetter can return a tuple:
from operator import itemgetter
myvalues = itemgetter(*mykeys)(mydict)
# use ...
Collection that allows only unique items in .NET?
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If all you need is to ensure uniqueness of elements, then HashSet is what you need.
What do you mean when you say "just a set implementation"? A set is (by definition) a collection of unique elements that doesn't save element ...