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dplyr: “Error in n(): function should not be called directly”
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I presume you have dplyr and plyr loaded in the same session. dplyr is not plyr. ddply is not a function in the dplyr package.
Both dplyr and plyr have the functions summarise/summarize.
Look at the results of conflicts() to see masked objects.
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Can I convert a C# string value to an escaped string literal
...point in reinventing stuff that .net can do for us
– Andy Morris
Jan 19 '10 at 13:58
17
Nice one,...
Python Dictionary Comprehension
...to add keys to an existing dictionary. Also, you have to specify the keys and values, although of course you can specify a dummy value if you like.
>>> d = {n: n**2 for n in range(5)}
>>> print d
{0: 0, 1: 1, 2: 4, 3: 9, 4: 16}
If you want to set them all to True:
>>>...
How to implement a queue using two stacks?
Suppose we have two stacks and no other temporary variable.
20 Answers
20
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How to sort an array in descending order in Ruby
...y
require 'benchmark'
ary = []
1000.times {
ary << {:bar => rand(1000)}
}
n = 500
Benchmark.bm(20) do |x|
x.report("sort") { n.times { ary.sort{ |a,b| b[:bar] <=> a[:bar] } } }
x.report("sort reverse") { n.times { ary.sort{ |a,b| a[:bar] <=> b[:bar...
Overloading Macro on Number of Arguments
I have two macros FOO2 and FOO3 :
8 Answers
8
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Replacing a 32-bit loop counter with 64-bit introduces crazy performance deviations with _mm_popcnt_
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Culprit: False Data Dependency (and the compiler isn't even aware of it)
On Sandy/Ivy Bridge and Haswell processors, the instruction:
popcnt src, dest
appears to have a false dependency on the destination register dest. Even though the instruction only...
Is there a way to measure how sorted a list is?
...Formally, let A(1), A(2), ..., A(n) be a sequence of n numbers.If i < j and A(i) > A(j), then the pair (i,j) is called an inversion of A.
The inversion number of a sequence is one common measure of its sortedness.Formally, the inversion number is defined to be the number of inversions, that is...
Finding three elements in an array whose sum is closest to a given number
Given an array of integers, A 1 , A 2 , ..., A n , including negatives and positives, and another integer S. Now we need to find three different integers in the array, whose sum is closest to the given integer S. If there exists more than one solution, any of them is ok.
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Is it correct to use JavaScript Array.sort() method for shuffling?
I was helping somebody out with his JavaScript code and my eyes were caught by a section that looked like that:
12 Answers
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