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How to count TRUE values in a logical vector
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There are some problems when logical vector contains NA values.
See for example:
z <- c(TRUE, FALSE, NA)
sum(z) # gives you NA
table(z)["TRUE"] # gives you 1
length(z[z == TRUE]) # f3lix answer, gives you 2 (because NA indexing returns values)
So I think the safest is to use na.rm = TRUE:
s...
HTTP POST with URL query parameters — good idea or not? [closed]
...a command to the resource to limit the scope of the current request. Typically, query strings are used to sort or filter a GET request (like ?page=1&sort=title) but I suppose it makes sense on a POST to also limit the scope (perhaps like ?action=delete&id=5).
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Preferred order of writing latitude & longitude tuples in GIS services
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EPSG:4326 specifically states that the coordinate order should be latitude, longitude. Many software packages still use longitude, latitude ordering. This situation has wreaked unimaginable havoc on project deadlines and programmer sanity.
Th...
Find the division remainder of a number
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you are looking for the modulo operator:
a % b
for example:
26 % 7
Of course, maybe they wanted you to implement it yourself, which wouldn't be too difficult either.
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How do I create a file and write to it in Java?
...te that each of the code samples below may throw IOException. Try/catch/finally blocks have been omitted for brevity. See this tutorial for information about exception handling.
Note that each of the code samples below will overwrite the file if it already exists
Creating a text file:
PrintWriter...
What is the difference between jQuery: text() and html() ?
...r .html()?
Answer: .html() is faster! See here a "behaviour test-kit" for all the question.
So, in conclusion, if you have "only a text", use html() method.
Note: Doesn't make sense? Remember that the .html() function is only a wrapper to .innerHTML, but in the .text() function jQuery adds an "enti...
How to enable PHP's openssl extension to install Composer?
I am trying to install Laravel in WAMP setup. I am getting a warning message for not enabling openssl which I had already done in WAMP.
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select、poll、epoll之间的区别总结[整理] - C/C++ - 清泛网 - 专注C/C++及内核技术
...1、select实现
select的调用过程如下所示：
（1）使用copy_from_user从用户空间拷贝fd_set到内核空间
（2）注册回调函数__pollwait
（3）遍历所有fd，调用其对应的poll方法（对于socket，这个poll方法是sock_poll，sock_poll根据情况会调用到...
How to export table as CSV with headings on Postgresql?
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COPY products_273 TO '/tmp/products_199.csv' WITH (FORMAT CSV, HEADER);
as described in the manual.
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How to reset Android Studio
...nt to reset Android Studio 0.2.13 to the default state. That means reset all settings, remove all projects, all gradle files so that it would act like a fresh installation. What steps do I have to follow to achieve this?
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