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Closed 10 years ago.
I have boxscore data from the NFL and some of the data is obviously incorrect. For example for some games the number of sacks is negative, which is impossible. This column is named SackNumOff. How do I change any negative values in this column to zero?
Something like this:
dat$columnname[dat$columnname < 0] = 0
Replaces all negative numbers by 0. The idea is that you can use a subset [] both to extract a subset and assign values to a subset.
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Closed 10 years ago.
Say, you have a Newton Method algorithms with 2 parameters of interest(a,b).
And I would like to plot their domain of convergence with x-axis = a, y-axis = b. Is there a really fast and simple to do this??? Any suggestions?
My algorithm will basically converge for some values of a & b. If I input (a,b), it will return (the number of iterations , value of a that it converge to, value of b that it converge to). Right now, I am thinking of setting up a for loop within another for loop, which run through all possible values of b first holding a fixed, and all possible values that a will converge holding b fixed.
However, my trouble is: how to identify whether a & b is converging or not. And is there a better way than using nested for loops????
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Closed 10 years ago.
In many programming problems (e.g. some Project Euler problems) we are asked to report the answer as the remainder left after dividing the answer by 1,000,000,007.
Why not any other number?
Edit:
2 years later, here's what I know: the number is a big prime, and any answer to such a question is so large that it makes sense to report a remainder instead (as the number may be too large for a native datatype to handle).
Let me play a telepathist. 1000...7 are prime numbers and 1000000007 is the biggest one that fits in 32-bit integer. Since prime numbers are used to calculate hash (by finding the remainder of the division by prime), 1000000007 is good for calculating 32-bit hash.
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Closed 10 years ago.
Tiles = {
{0,0,0,0,0,0,0,0,0,0},
{0,2,2,2,2,2,2,2,2,0},
{0,3,0,0,2,4,2,2,2,0},
{0,0,2,0,0,0,2,2,2,0},
{0,0,2,2,2,0,2,2,2,0},
{0,0,0,0,2,0,2,2,2,0},
{0,0,2,2,2,0,2,2,2,0},
{0,0,0,0,0,0,0,0,0,0}
}
0 is not clickable, other is clickable, otherways 0 is walkable an other is not, weh i click Tiles[3][2] (number 3) then Tiles[3][6] (number 4), i want to connect that 2 tile through walkable tile, the problem is i dont need a shortest solution, instead i need solution that have 2 or less corner (turning), i have spent 3 days to imagine and googling the algorithm, but no luck, can someone give me a clue or article about that, and i use lua but other language is still i appreciate.
Transform your grid into a graph using the following rules:
Every walkable tile in the grid corresponds to a node in the graph.
Two nodes are connected (with weight 1) in the graph if they are in the same row or column in the grid and every tile between them in the grid is walkable.
The shortest path in the graph corresponds to the path with fewest corners in the grid.
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Closed 11 years ago.
How to calculate standard deviation of a single decimal value, in C#
I do it in SAS code as the following:
std(x y m ) = xSTD YSTD mSDT;
It is simply 0 see the wiki article.
Let X be the number
Calculate EV of [x] which is x
Subtract EV from each element in set which is [0]
Take the average of [0] which is 0
Take the square root of 0 which is 0