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How do you detect where two line segments intersect? [closed]
... approach to this problem that uses vector cross products. Define the 2-dimensional vector cross product v × w to be vx wy − vy wx.
Suppose the two line segments run from p to p + r and from q to q + s. Then any point on the first line is representable as p + t r (for a scalar par...
“using namespace” in c++ headers
In all our c++ courses, all the teachers always put using namespace std; right after the #include s in their .h files. This seems to me to be dangerous since then by including that header in another program I will get the namespace imported into my program, maybe without realizing, intending or...
Argument list too long error for rm, cp, mv commands
I have several hundred PDFs under a directory in UNIX. The names of the PDFs are really long (approx. 60 chars).
27 Answers...
How to determine whether a Pandas Column contains a particular value
...lumn 43 in df['id'] it still returned True . When I subset to a data frame only containing entries matching the missing id df[df['id'] == 43] there are, obviously, no entries in it. How to I determine if a column in a Pandas data frame contains a particular value and why doesn't my current meth...
How to convert AAR to JAR
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The AAR file consists of a JAR file and some resource files (it is basically a standard zip file with a custom file extension). Here are the steps to convert:
Extract the AAR file using standard zip extract (rename it to *.zip to make it easier)
Find the classes.ja...
C-like structures in Python
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Use a named tuple, which was added to the collections module in the standard library in Python 2.6. It's also possible to use Raymond Hettinger's named tuple recipe if you need to support Python 2.4.
It's nice for your basic example...
How to amend several commits in Git to change author
... series of commits in Git and I realise now that I forgot to set my user name and user email properties correctly (new machine). I have not yet pushed these commits to my repository, so how can I correct these commits before I do so (only the 3 latest commits on the master branch)?
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How to force 'cp' to overwrite directory instead of creating another one inside?
...ered Jun 30 '14 at 8:45
Saurabh MeshramSaurabh Meshram
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“#include” a text file in a C program as a char[]
...way to include an entire text file as a string in a C program at compile-time?
17 Answers
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How to get the instance id from within an ec2 instance?
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See the EC2 documentation on the subject.
Run:
wget -q -O - http://169.254.169.254/latest/meta-data/instance-id
If you need programatic access to the instance ID from within a script,
die() { status=$1; shift; echo "FATAL: $*"; exit $st...