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Sample random rows in dataframe
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460
First make some data:
> df = data.frame(matrix(rnorm(20), nrow=10))
> df
X1 ...
Checking for empty arrays: count vs empty
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answered Feb 7 '10 at 6:21
prodigitalsonprodigitalson
57.2k77 gold badges8888 silver badges108108 bronze badges
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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...
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 to host a Node.Js application in shared hosting [closed]
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160
You can run node.js server on a typical shared hosting with Linux, Apache and PHP (LAMP). I hav...
Django Server Error: port is already in use
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A more simple solution just type sudo fuser -k 8000/tcp.
This should kill all the processes associated with port 8000.
EDIT:
For osx users you can use sudo lsof -t -i tcp:8000 | xargs kill -9
sha...
Spring RestTemplate - how to enable full debugging/logging of requests/responses?
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edited Oct 24 '18 at 8:00
answered Oct 8 '15 at 7:54
sof...
Using async/await for multiple tasks
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edited Jul 7 '16 at 10:41
answered Sep 9 '12 at 11:35
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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...
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...