大约有 47,000 项符合查询结果（耗时：0.0469秒） [XML]
Sample random rows in dataframe
...
460
First make some data:
> df = data.frame(matrix(rnorm(20), nrow=10))
> df
X1 ...
How do I get bit-by-bit data from an integer value in C?
...wanted){
int *bits = malloc(sizeof(int) * bitswanted);
int k;
for(k=0; k<bitswanted; k++){
int mask = 1 << k;
int masked_n = n & mask;
int thebit = masked_n >> k;
bits[k] = thebit;
}
return bits;
}
int main(){
int n=7;
int bitswanted = 5;
int...
Fastest way to list all primes below N
...
+100
Warning: timeit results may vary due to differences in hardware or
version of Python.
Below is a script which compares a number of...
How to host a Node.Js application in shared hosting [closed]
...
160
You can run node.js server on a typical shared hosting with Linux, Apache and PHP (LAMP). I hav...
Dynamically select data frame columns using $ and a character value
...itten as
`$`(df , V1)
or indeed
`$`(df , "V1")
But...
`$`(df , paste0("V1") )
...for instance will never work, nor will anything else that must first be evaluated in the second argument. You may only pass a string which is never evaluated.
Instead use [ (or [[ if you want to extract only...
How can I quickly sum all numbers in a file?
...;
}
-e syntax OK
Just for giggles, I tried this with a file containing 1,000,000 numbers (in the range 0 - 9,999). On my Mac Pro, it returns virtually instantaneously. That's too bad, because I was hoping using mmap would be really fast, but it's just the same time:
use 5.010;
use File::Map qw(ma...
Kill a Process by Looking up the Port being used by it from a .BAT
In Windows what can look for port 8080 and try to kill the process it is using through a .BAT file?
14 Answers
...
Using async/await for multiple tasks
... |
edited Jul 7 '16 at 10:41
answered Sep 9 '12 at 11:35
...
Efficient Algorithm for Bit Reversal (from MSB->LSB to LSB->MSB) in C
...here):
unsigned int
reverse(register unsigned int x)
{
x = (((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1));
x = (((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2));
x = (((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4));
...
Inline labels in Matplotlib
...e(np.int32)
# mask stuff outside plot
mask = (xy[:,0] >= 0) & (xy[:,0] < N) & (xy[:,1] >= 0) & (xy[:,1] < N)
xy = xy[mask]
# add to pop
for p in xy:
pop[l][tuple(p)] = 1.0
# find whitespace, nice place for label...