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R programming: How do I get Euler's number?
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150
The R expression
exp(1)
represents e, and
exp(2)
represents e^2.
This works because exp...
Is git's semi-secret empty tree object reliable, and why is there not a symbolic name for it?
Git has a well-known, or at least sort-of-well-known, empty tree whose SHA1 is:
3 Answers
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How to backup a local Git repository?
...thub.
#!/usr/bin/env ruby
#
# For documentation please sea man git-backup(1)
#
# TODO:
# - make it a class rather than a function
# - check the standard format of git warnings to be conform
# - do better checking for git repo than calling git status
# - if multiple entries found in config file, spe...
Should we @Override an interface's method implementation?
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15 Answers
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Active
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Paperclip::Errors::MissingRequiredValidatorError with Rails 4
...line to your Post model, after specifying has_attached_file :image
Option 1: Validate content type
validates_attachment_content_type :image, :content_type => ["image/jpg", "image/jpeg", "image/png", "image/gif"]
-OR- another way
validates_attachment :image, content_type: { content_type: ["im...
Running multiple commands in one line in shell
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edited Apr 26 '14 at 1:06
answered Feb 27 '11 at 1:44
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How can I get the diff between all the commits that occurred between two dates with Git?
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11 Answers
11
Active
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Pandas aggregate count distinct
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153
How about either of:
>>> df
date duration user_id
0 2013-04-01 30 ...
64-bit version of Boost for 64-bit windows
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answered Feb 24 '10 at 14:01
Adrian ConlonAdrian Conlon
3,92111 gold badge1919 silver badges1717 bronze badges
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Python's json module, converts int dictionary keys to strings
... for the given language, are strings (or "scalars" in Perl). In perl $foo{1}, $foo{1.0}, and $foo{"1"} are all references to the same mapping in %foo --- the key is evaluated as a scalar!
JSON started as a Javascript serialization technology. (JSON stands for JavaScript Object Notation.) Naturall...