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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...Y] is a join, looking up X's rows using Y (or Y's key if it has one) as an index.
Y[X] is a join, looking up Y's rows using X (or X's key if it has one)
merge(X,Y) does both ways at the same time. The number of rows of X[Y] and Y[X] usually differ, whereas the number of rows returned by me...
How to automatically generate a stacktrace when my program crashes
...does not contain a field named eip. There is now an array that needs to be indexed, uc_mcontext.gregs[REG_EIP] is the equivalent.
– mmlb
Dec 14 '12 at 14:57
...
What does “dereferencing” a pointer mean?
...at the pointer points to - the contents of the address with that numerical index - then you dereference the pointer.
Different computer languages have different notations to tell the compiler or interpreter that you're now interested in the pointed-to object's (current) value - I focus below on C a...
What is the Sign Off feature in Git for?
...headers and
associated meaning for them.
See: https://git.wiki.kernel.org/index.php/CommitMessageConventions
Moral of the story
It is my impression that, although the initial motivation for this
particular metadata was some legal issues (judging by the other
answers), the practice of such metadat...
Algorithm to compare two images
...tricky).
http://en.wikipedia.org/wiki/RGB_color_space
http://upvector.com/index.php?section=tutorials&subsection=tutorials/colorspace
Another example involves something called the Hough Transform. This transform essentially decomposes an image into a set of lines. You can then take some of...
Why do we use __init__ in Python classes?
...s MyInteger:
def __init__(self, newvalue)
# imagine self as an index card.
# under the heading of "value", we will write
# the contents of the variable newvalue.
self.value = newvalue
def add(self, other):
# when an integer wants to add itself to anoth...
PHP mail function doesn't complete sending of e-mail
I've tried creating a simple mail form. The form itself is on my index.html page, but it submits to a separate "thank you for your submission" page, thankyou.php , where the above PHP code is embedded.
The code submits perfectly, but never sends an email. How can I fix this?
...
Difference between CouchDB and Couchbase
...e Couchbase Server 2.0 release (currently at Developer Preview 3) will add index and query functionality. While Couchbase Server 2.0 will incorporate substantial technology from the CouchDB project, it will not be upward compatible with CouchDB and it shouldn’t be viewed as a “version of CouchD...
ab load testing
...orld results, you'll want to test Wordpress instead of some static HTML or index.php file because you need to know how everything performs together: including complex PHP code, and multiple MySQL queries...
For example here is the results of testing a fresh install of Wordpress on the same system a...
How to encrypt String in Java
...ad what is written in PDF-417 2D barcodes. And anyway, there are only some indexes not crucial to anyone...
– ante.sabo
Oct 11 '12 at 16:16
2
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