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Remove duplicated rows using dplyr
...ction for this purpose.
Original answer below:
library(dplyr)
set.seed(123)
df <- data.frame(
x = sample(0:1, 10, replace = T),
y = sample(0:1, 10, replace = T),
z = 1:10
)
One approach would be to group, and then only keep the first row:
df %>% group_by(x, y) %>% filter(row_nu...
Check if $_POST exists
...ugustus Francis's answer, empty() is not correct for choice #1, because in php, the string '0' is equivalent to false - and empty() returns true for all values equivalent to false. So using empty, the code would skip printing if the value was '0'. If you want to exclude the empty string, see Augustu...
GestureDetect 手势检测扩展：识别滑动、点击和长按手势 · App Inventor 2 中文网
...势检测原理
性能优化建议
常见问题
Q: 手势检测不灵敏怎么办？
Q: 手势在按钮上不起作用？
Q: 可以在滚动排列中使用吗？
Q: 如何在同一个组件上检测多种手势？
...
How to convert array to SimpleXML
How can I convert an array to a SimpleXML object in PHP?
33 Answers
33
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When to use single quotes, double quotes, and backticks in MySQL
...delimiter in date strings.
So using your example, I would double-quote the PHP string and use single quotes on the values 'val1', 'val2'. NULL is a MySQL keyword, and a special (non)-value, and is therefore unquoted.
None of these table or column identifiers are reserved words or make use of charac...
How to catch curl errors in PHP
I am using PHP curl functions to post data to the web server from my local machine. My code is as follows:
5 Answers
...
nginx - client_max_body_size has no effect
...etc/nginx/conf.d/default.conf file)
Also, make certain that your server's php.ini file is consistent with these NGINX settings. In my case, I changed the setting in php.ini's File_Uploads section to read:
upload_max_filesize = 200M
Note: if you are managing an ISPconfig 3 setup (my setup is on...
PHP method chaining?
I am using PHP 5 and I've heard of a new featured in the object-oriented approach, called 'method chaining'. What is it exactly? How do I implement it?
...
How can I run a PHP script in the background after a form is submitted?
...using the following line to invoke the email script:
shell_exec("/path/to/php /path/to/send_notifications.php '".$post_id."' 'alert' >> /path/to/alert_log/paging.log &");
It is important to notice the & at the end of the command (as pointed out by @netcoder). This UNIX command runs ...
mysqli_fetch_assoc() expects parameter / Call to a member function bind_param() errors. How to get t
...s the reason. Unfortunately, by default such errors are not transferred to PHP, and all you've got is a cryptic error message mentioned above. Hence it is very important to configure PHP and MySQLi to report MySQL errors to you. And once you get the error message, fixing it will be a piece of cake....