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How to test if list element exists?
...es(foo) # TRUE
"b" %in% names(foo) # TRUE
"c" %in% names(foo) # FALSE
...and foo[["a"]] is safer than foo$a, since the latter uses partial matching and thus might also match a longer name:
x <- list(abc=4)
x$a # 4, since it partially matches abc
x[["a"]] # NULL, no match
[UPDATE] So, back t...
Private virtual method in C++
...ected you're implicitly trusting the writer of any derived class to understand and properly use the protected internals, just the way a friend declaration implies a deeper trust for private members.
Users who get bad behavior from violating that trust (e.g. labeled 'clueless' by not bothering to r...
How to construct a set out of list items in python?
I have a list of filenames in python and I would want to construct a set out of all the filenames.
6 Answers
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Spark java.lang.OutOfMemoryError: Java heap space
... suggestions:
If your nodes are configured to have 6g maximum for Spark (and are leaving a little for other processes), then use 6g rather than 4g, spark.executor.memory=6g. Make sure you're using as much memory as possible by checking the UI (it will say how much mem you're using)
Try using more ...
How to get the last date of a particular month with JodaTime?
I need to get the first date (as org.joda.time.LocalDate ) of a month and the last one. Getting the first is trivial, but getting the last seems to need some logic as months have different length and February length even varies over years. Is there a mechanism for this already built in to JodaTime ...
Which rows are returned when using LIMIT with OFFSET in MySQL?
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It will return 18 results starting on record #9 and finishing on record #26.
Start by reading the query from offset. First you offset by 8, which means you skip the first 8 results of the query. Then you limit by 18. Which means you consider records 9, 10, 11, 12, 13, 14,...
How do I get the path of a process in Unix / Linux
...symlink /proc/<pid>/exe has the path of the executable. Use the command readlink -f /proc/<pid>/exe to get the value.
On AIX, this file does not exist. You could compare cksum <actual path to binary> and cksum /proc/<pid>/object/a.out.
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What is a pre-revprop-change hook in SVN, and how do I create it?
I wanted to edit a log comment in the repository browser and received an error message that no pre-revprop-change hook exists for the repository. Besides having a scary name, what is a pre-revprop-change hook, and how do I create it?
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How to track child process using strace?
...ending thread, I had to tediously search for the parent thread, then the grandparent thread, and so on all the way to the root process.
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Using jQuery how to get click coordinates on the target element
I have the following event handler for my html element
6 Answers
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