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How do I make a matrix from a list of vectors in R?
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124
One option is to use do.call():
> do.call(rbind, a)
[,1] [,2] [,3] [,4] [,5] [,6]
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Determining complexity for recursive functions (Big O notation)
...he time complexity, in Big O notation, for each function:
int recursiveFun1(int n)
{
if (n <= 0)
return 1;
else
return 1 + recursiveFun1(n-1);
}
This function is being called recursively n times before reaching the base case so its O(n), often called linear.
int recursi...
[since C++11] std::array的使用 - C/C++ - 清泛网 - 专注C/C++及内核技术
[since C++11] std::array的使用learning-using-cpp11-stl-array 前言本文总结了STL中的序列式容器array的用法及注意事项。array的出现代表着C++的代码更进一步现代化，就像std::string的出现代替了c风格字符串并且能和STL配合工作一样，array的 #...
Applying a function to every row of a table using dplyr?
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edited Aug 6 '19 at 3:20
answered Jul 14 '14 at 0:20
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What is the ultimate postal code and zip regex?
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132
There is none.
Postal/zip codes around the world don't follow a common pattern. In some count...
What is the optimal Jewish toenail cutting algorithm?
...ule. Luckily, humans only have five toes per foot*, so there are only 5! = 120 unrestricted sequences.
Python example:
#seq is only valid when consecutive elements in the list differ by at least two.
def isValid(seq):
for i in range(len(seq)-1):
a = seq[i]
b = seq[i+1]
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All combinations of a list of lists
... need itertools.product:
>>> import itertools
>>> a = [[1,2,3],[4,5,6],[7,8,9,10]]
>>> list(itertools.product(*a))
[(1, 4, 7), (1, 4, 8), (1, 4, 9), (1, 4, 10), (1, 5, 7), (1, 5, 8), (1, 5, 9), (1, 5, 10), (1, 6, 7), (1, 6, 8), (1, 6, 9), (1, 6, 10), (2, 4, 7), (2, 4, 8),...
Finding all possible combinations of numbers to reach a given sum
... range(len(numbers)):
n = numbers[i]
remaining = numbers[i+1:]
subset_sum(remaining, target, partial + [n])
if __name__ == "__main__":
subset_sum([3,9,8,4,5,7,10],15)
#Outputs:
#sum([3, 8, 4])=15
#sum([3, 5, 7])=15
#sum([8, 7])=15
#sum([5, 10])=15
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How to slice an array in Bash
Looking the "Array" section in the bash(1) man page, I didn't find a way to slice an array.
4 Answers
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Why does [5,6,8,7][1,2] = 8 in JavaScript?
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[1,2,3,4,5,6][1,2,3];
^ ^
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array + — array subscript access operation,
where index is `1,2,3`,
which is an expression that evaluates to `3`.
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