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Is R's apply family more than syntactic sugar?
...id = rep(letters[1:10], 100000),
value = rnorm(1000000))
f1 <- function(x)
tapply(x$value, x$id, sum)
f2 <- function(x){
res <- 0
for(i in seq_along(l <- unique(x$id)))
res[i] <- sum(x$value[x$id == l[i]])
names(res) <- l
res
}
library(...
What does ~> mean in a gem file [duplicate]
... answered Feb 24 '11 at 7:29
Pan ThomakosPan Thomakos
31.9k88 gold badges8282 silver badges8484 bronze badges
...
微软Win7/Win8自带 tsmmc.msc 远程桌面管理工具（多账号的mstsc远程桌面） ...
...
如果这个地址不可以也可以从我的百度网盘下载
http://pan.baidu.com/share/home?uk=1679283288
Windows 系统原本均自带了「远程桌面」的功能，你不需要额外安装软件即可实现控制其他 Windows 电脑或者作为被控端使用。现在使用微软...
Lua简明教程 - 脚本技术 - 清泛IT论坛，有思想、有深度
...动用MetaTable，如下所示：fraction_op={}
function fraction_op.__add(f1, f2)
ret = {}
ret.numerator = f1.numerator * f2.denominator + f2.numerator * f1.denominator
ret.denominator = f1.denominator * f2.denominator
return ret
end复制代...
How to search and replace text in a file?
...
You can do the replacement like this
f1 = open('file1.txt', 'r')
f2 = open('file2.txt', 'w')
for line in f1:
f2.write(line.replace('old_text', 'new_text'))
f1.close()
f2.close()
sha...
Select N random elements from a List in C#
...
OK a year late but... Doesn't this pan out to @ersin's rather shorter answer, and won't it fail if you get a repeated random number (Where Ersin's will have a bias towards the first item of a repeated pair)
– Andiih
Sep 8...
Character reading from file in Python
...s you to specify file's encoding:
>>> import codecs
>>> f1 = codecs.open(file1, "r", "utf-8")
>>> text = f1.read()
>>> print type(text)
<type 'unicode'>
>>> print text.encode('utf-8')
I don‘t like this
...
How do I create a list of random numbers without duplicates?
...lect random lines from the saved list in memory. For example:
all_lines = f1.readlines()
for i in range(50):
lines = random.sample(all_lines, 40)
This way, you only need to actually read from the file once, before your loop. It's much more efficient to do this than to seek back to the start o...
What is the difference between quiet NaN and signaling NaN?
...
if (argc == 1) {
feenableexcept(FE_INVALID);
}
float f1 = 0.0 / f0;
printf("f1 %f\n", f1);
feenableexcept(FE_INVALID);
float f2 = f1 + 1.0;
printf("f2 %f\n", f2);
}
compile:
gcc -ggdb3 -O0 -std=c99 -Wall -Wextra -pedantic -o main.out main.c -lm
then:
./ma...
How can I benchmark JavaScript code? [closed]
...
TypeScript version: pastebin.com/gCs9CB5F
– Alexander Taylor
Jun 14 '17 at 18:51
1
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