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pandas GroupBy columns with NaN (missing) values
...the same placeholder hack).
However, as described in another answer, from pandas 1.1 you have better control over this behavior, NA values are now allowed in the grouper using dropna=False
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Logic to test that 3 of 4 are True
I want to return True if and only if 3 out of 4 boolean values are true.
27 Answers
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&& (AND) and || (OR) in IF statements
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No, it will not be evaluated. And this is very useful. For example, if you need to test whether a String is not null or empty, you can write:
if (str != null && !str.isEmpty()) {
doSomethingWith(str.charAt(0));
}
or, the other way around
if ...
PSQLException: current transaction is aborted, commands ignored until end of transaction block
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I got this error using Java and PostgreSQL doing an insert on a table. I will illustrate how you can reproduce this error:
org.postgresql.util.PSQLException: ERROR:
current transaction is aborted, commands ignored until end of transaction block
Summa...
How to benchmark efficiency of PHP script
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If you actually want to benchmark real world code, use tools like Xdebug and XHProf.
Xdebug is great for when you're working in dev/staging, and XHProf is a great tool for production and it's safe to run it there (as long as you read the instructions). The results of any one single page load aren...
What does $.when.apply($, someArray) do?
I'm reading about Deferreds and Promises and keep coming across $.when.apply($, someArray) . I'm a little unclear on what this does exactly, looking for an explanation that one line works exactly (not the entire code snippet). Here's some context:
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“CAUTION: provisional headers are shown” in Chrome debugger
...r Latest Versions of chrome
Type chrome://net-export/ in the address bar and hit enter.
Start Recording. And save Recording file to local.
Open the page that is showing problems.
Go back to net-internals
You can view Recorded Log file Here https://netlog-viewer.appspot.com/#import
click on events ...
What is the difference between ManualResetEvent and AutoResetEvent in .NET?
I have read the documentation on this and I think I understand. An AutoResetEvent resets when the code passes through event.WaitOne() , but a ManualResetEvent does not.
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Remove all special characters from a string [duplicate]
...with URLs, I want to be able to convert titles that could contain anything and have them stripped of all special characters so they only have letters and numbers and of course I would like to replace spaces with hyphens.
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How do I move an existing Git submodule within a Git repository?
...ules:
Since git 1.8.5, git mv old/submod new/submod works as expected and does all the plumbing for you. You might want to use git 1.9.3 or newer, because it includes fixes for submodule moving.
The process is similar to how you'd remove a submodule (see How do I remove a submodule?):
Edi...