大约有 500 项符合查询结果（耗时：0.0146秒） [XML]
Xcode doesn't show the line that causes a crash
...oopDoBlocks + 356
16 CoreFoundation 0x000000010e7e5e65 __CFRunLoopRun + 901
17 CoreFoundation 0x000000010e7e5884 CFRunLoopRunSpecific + 420
18 GraphicsServices 0x00000001126d9a6f GSEventRunModal + 161
19 UIKit ...
Evaluate expression given as a string
...here's no nice formatting):
q5 <- quote(5+5)
str(q5)
# language 5 + 5
e5 <- expression(5+5)
str(e5)
# expression(5 + 5)
and if you get more experienced you'll learn that q5 is a "call" whereas e5 is an "expression", and even that e5[[1]] is identical to q5:
identical(q5, e5[[1]])
# [1] TR...
Speed up the loop operation in R
...kes 28 seconds to complete
system.time({
a <- NULL
for(i in 1:1e5)a[i] <- i
})
user system elapsed
28.36 0.07 28.61
You can get an almost 100-times improvement by the simple action of pre-allocating memory:
system.time({
a <- rep(1, 1e5)
for(i in 1:1e5)a[i] ...
How to find out which version of the .NET Framework an executable needs to run?
...adata version: v2.0.50727
.assembly extern mscorlib
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 ) // .z\V.4..
.ver 2:0:0:0
}
.assembly extern System
{
.publickeytoken = (B7 7A 5C 56 19 34 E0 89 ) // .z\V.4..
.ver 2:0:0:0
}
Reflector:
.modul...
Understanding exactly when a data.table is a reference to (vs a copy of) another data.table
..., 2), b = c(11, 12))
newDT <- DT
.Internal(inspect(DT))
# @0000000003B7E2A0 19 VECSXP g0c7 [OBJ,NAM(2),ATT] (len=2, tl=100)
# @00000000040C2288 14 REALSXP g0c2 [NAM(2)] (len=2, tl=0) 1,2
# @00000000040C2250 14 REALSXP g0c2 [NAM(2)] (len=2, tl=0) 11,12
# ATTRIB: # ..snip..
.Internal(inspe...
Is R's apply family more than syntactic sugar?
...pe which makes it much faster.
foo <- function(x) x+1
y <- numeric(1e6)
system.time({z <- numeric(1e6); for(i in y) z[i] <- foo(i)})
# user system elapsed
# 3.54 0.00 3.53
system.time(z <- lapply(y, foo))
# user system elapsed
# 2.89 0.00 2.91
system.time(z...
Why does git revert complain about a missing -m option?
...(HEAD, master) Merge branch 'otherguy'
|\
| * c7256de (otherguy) bar
* | b7e7176 baz
|/
* 9968f79 foo
Note: git lola is a non-standard but useful alias.
No dice with git revert:
$ git revert HEAD
fatal: Commit 2582152... is a merge but no -m option was given.
Charles Bailey gave an excellent...
Why is Go so slow (compared to Java)?
... 1344 5.76 76% 71% 74% 73%
C gcc 1.36 2,800 1993 5.26 96% 97% 100% 97%
regex-dna
1.64x
Go 3.89 369,380 1229 8.29 43% 53% 61% 82%
C gcc 2.43 339,000 2579 5.68 46% 70% 51% 72%
fannkuch-redux
1.72x
Go 15.59 952 900 62.08 100% 100% 100% 100%
C gcc...
Find Results not displaying Results
...dows Registry Editor Version 5.00
[HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{73B7DC00-F498-4ABD-AB79-D07AFD52F395}]
@="PSFactoryBuffer"
[HKEY_CLASSES_ROOT\Wow6432Node\CLSID\{73B7DC00-F498-4ABD-AB79-D07AFD52F395}\InProcServer32]
@="C:\\Program Files (x86)\\Common Files\\Microsoft Shared\\MSEnv\\TextMgrP...
How to clear basic authentication details in chrome
..."GET",str,true);
xmlhttp.setRequestHeader("Authorization","Basic YXNkc2E6")
xmlhttp.send();
return false;
}
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