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PHP Session Security
... a piece of scotch tape across your door and saying it will prevent people from breaking in.
– rook
Apr 27 '10 at 23:59
8
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dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...ime, especially since your data are already factored, you can use complete from "tidyr" to get what you might be looking for:
library(tidyr)
df %>%
group_by(b) %>%
summarise(count_a=length(a)) %>%
complete(b)
# Source: local data frame [3 x 2]
#
# b count_a
# (fctr) (int)...
Is GridFS fast and reliable enough for production?
...le. It doesn't matter if the image is lost since we will download it again from the merchants website. Pragmatically, we could consider that our server is a simple image cache server.
– Manu Eidenberger
May 12 '11 at 21:17
...
android splash screen sizes for ldpi,mdpi, hdpi, xhdpi displays ? - eg : 1024X768 pixels for ldpi
...fine xxhdpi as ~480 DPI. They don't provide a minimum screen size for this from what I can see.
– Alex Wiese
Oct 4 '13 at 0:38
8
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Does the default constructor initialize built-in types?
...ater end up in a situation where you expect zeroes but a non-zero leftover from an earlier object sits.
So, why is this then, isn't all new-ed data newly allocated? Yes, but not always from the OS. The OS tends to work with larger chunks of memory (e.g. 4MB at a time) so all the tiny one-word-here-...
How to append rows to an R data frame
... <- i
}
data.frame(x, y, stringsAsFactors=FALSE)
}
microbenchmark from the "microbenchmark" package will give us more comprehensive insight than system.time:
library(microbenchmark)
microbenchmark(f1(1000), f3(1000), f4(1000), times = 5)
# Unit: milliseconds
# expr min ...
PHP编译configure时常见错误 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...d.
apt-get install libpng12-dev
6、configure: error: cannot find output from lex; giving up
yum -y install flex
7、configure: error: mod_deflate has been requested but can not be built due to prerequisite failures
centos: yum -y install zlib-devel openssl-devel
debian: apt-get install zlib1g...
When is memoization automatic in GHC Haskell?
...new version is much less efficient because it will have to read about 1 GB from memory where y is stored, while the original version would run in constant space and fit in the processor's cache. In fact, under GHC 6.12.1, the function f is almost twice as fast when compiled without optimizations th...
How to stop an unstoppable zombie job on Jenkins without restarting the server?
...hudson.model.Result.ABORTED, new java.io.IOException("Aborting build"));
From https://issues.jenkins-ci.org/browse/JENKINS-43020
If you aren't sure what the full name (path) of the job is, you may use the following snippet to list the full name of all items:
Jenkins.instance.getAllItems(Abstra...
Begin, Rescue and Ensure in Ruby?
...n leave out the exception class, in which case all exceptions that inherit from StandardError will be caught. (Please note that this does not mean that all exceptions are caught, because there are exceptions which are instances of Exception but not StandardError. Mostly very severe exceptions that c...