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How to display unique records from a has_many through relationship?
...ay to display unique records from a has_many, through relationship in Rails3.
4 Answers
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Reshaping data.frame from wide to long format
...:
reshape(d,
direction = "long",
varying = list(names(d)[3:7]),
v.names = "Value",
idvar = c("Code", "Country"),
timevar = "Year",
times = 1950:1954)
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How to use arguments from previous command?
...w see:
$ echo a
without pressing Enter yet, do the following
Press Alt-3 Alt-Ctrl-y
Press Alt-- 2 Alt-Ctrl-y
Now you will see:
$ echo ace
By the way, you could have put the echo on the line by selecting argument 0:
Press Alt-0 Alt-Ctrl-y
Edit:
To answer the question you added to your or...
Python integer division yields float
...
Take a look at PEP-238: Changing the Division Operator
The // operator will be available to request floor division unambiguously.
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How to tell Maven to disregard SSL errors (and trusting all certs)?
...
239
You can disable SSL certificate checking by adding one or more of these command line parameters...
What are the differences between vector and list data types in R?
...tors are "atomic vectors" in strict R parlance:
aaa <- vector("list", 3)
is.list(aaa) #TRUE
is.vector(aaa) #TRUE
Lists are a "recursive" type (of vector) whereas atomic vectors are not:
is.recursive(aaa) # TRUE
is.atomic(aaa) # FALSE
You process data objects with different functions...
Is MATLAB OOP slow or am I doing something wrong?
...ction/method 100000 times
nop() function: 0.02261 sec 0.23 usec per call
nop1-5() functions: 0.02182 sec 0.22 usec per call
nop() subfunction: 0.02244 sec 0.22 usec per call
@()[] anonymous function: 0.08461 sec 0.85 usec per call
nop(obj) metho...
What is more efficient? Using pow to square or just multiply it with itself?
... elapsed << " "; \
\
return x; \
}
TEST(1, b)
TEST(2, b*b)
TEST(3, b*b*b)
TEST(4, b*b*b*b)
TEST(5, b*b*b*b*b)
template <int exponent>
double testpow(double base, long loops)
{
double x = 0.0;
boost::posix_time::ptime startTime = now();
for (long i=0; i<loops; ++i)
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What is the difference between an expression and a statement in Python?
...duced to some kind of "value", which can be any Python object. Examples:
3 + 5
map(lambda x: x*x, range(10))
[a.x for a in some_iterable]
yield 7
Statements (see 1, 2), on the other hand, are everything that can make up a line (or several lines) of Python code. Note that expressions are stateme...
What is the purpose of the EBP frame pointer register?
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edited Sep 13 '17 at 18:21
answered Feb 23 '09 at 20:55
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