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Why are elementwise additions much faster in separate loops than in a combined loop?
...from a page-boundary.
Here's the test code:
int main(){
const int n = 100000;
#ifdef ALLOCATE_SEPERATE
double *a1 = (double*)malloc(n * sizeof(double));
double *b1 = (double*)malloc(n * sizeof(double));
double *c1 = (double*)malloc(n * sizeof(double));
double *d1 = (double*)mall...
Filter rows which contain a certain string
...6.480 1.513 16.195 0.248
# 1 str_detect 10 10.891 1.000 9.594 1.281
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How to read a large file - line by line?
...dd it last, not first. First show the proper way.
– m000
Sep 20 '13 at 22:03
7
@katrielalex revis...
Multiple INSERT statements vs. single INSERT with multiple VALUES
I'm running a performance comparison between using 1000 INSERT statements:
4 Answers
4...
What's the fastest way to merge/join data.frames in R?
...rm(N))
d2 <- data.frame(x=sample(N,N), y2=rnorm(N))
g1 <- sample(1:1000, N, replace = TRUE)
g2<- sample(1:1000, N, replace = TRUE)
d <- data.frame(d1, g1, g2)
library(rbenchmark)
benchmark(replications = 1, order = "elapsed",
merge = merge(d1, d2),
plyr = join(d1, d2),
data.t...
How do I make a list of data frames?
...m(50))
But who does only one simulation? You want to do this 100 times, 1000 times, more! But you don't want 10,000 data frames in your workspace. Use replicate and put them in a list:
sim_list = replicate(n = 10,
expr = {data.frame(x = rnorm(50), y = rnorm(50))},
...
What is the significance of ProjectTypeGuids tag in the visual studio project file
...4A-11D0-8D11-00A0C91BC942}
Web Application {349C5851-65DF-11DA-9384-00065B846F21}
Web Site {E24C65DC-7377-472B-9ABA-BC803B73C61A}
WCF {3D9AD99F-2412-4246-B90B-4EAA41C64699}
WPF {60DC8134-EBA5-43B8-BCC9-BB4BC16C2548}
XNA (Windows) {6...
How to parse/format dates with LocalDateTime? (Java 8)
...
@micha what if i have "2016-12-31T07:59:00.000Z" this date formate?
– Dawood Ahmed
Apr 26 '16 at 12:29
15
...
What is polymorphism, what is it for, and how is it used?
...c are instantiated.
petraeus.Advise(); // # Petraeus says send 100,000 troops to Fallujah
condolezza.Advise(); // # she says negotiate trade deal with Iran
healthOfficials.Advise(); // # they say we need to spend $50 billion on ObamaCare
}
}
This approach allows the pre...
Caveats of select/poll vs. epoll reactors in Twisted
...huge number of file descriptors in a few dozen kilobytes (roughly 20k per 1000 file descriptors, I think). And you can also throw in the fact that you have to spend all 384 of those bytes with select if you only want to monitor one file descriptor but its value happens to be 1024, wheras with epoll...