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How to delete a row by reference in data.table?
...el.idxs' vs. 'keep.idxs'
keep.idxs <- setdiff(DT[, .I], del.idxs); # select row indexes to keep
cols = names(DT);
DT.subset <- data.table(DT[[1]][keep.idxs]); # this is the subsetted table
setnames(DT.subset, cols[1]);
for (col in cols[2:length(cols)]) {
DT.subset[, (col) := DT[...
Why does Popen.communicate() return b'hi\n' instead of 'hi'?
...ing of the bytes you received from the subprocess, you can use decode() to convert them into a printable str:
>>> print(b'hi\n'.decode('ascii'))
hi
Of course, this specific example only works if you actually are receiving ASCII from the subprocess. If it's not ASCII, you'll get an excep...
Select Last Row in the Table
I would like to retrieve the last file inserted into my table. I know that the method first() exists and provides you with the first file in the table but I don't know how to get the last insert.
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How to attach javadoc or sources to jars in libs folder?
...-open the Eclipse project! Optionally, refresh the project by pressing F5.
Select an object of the linked library in the source code.
Open the Javadoc view in Eclipse to check the documentation (see screenshot).
Open the source code declaration (default shortcut: F3) of the selected object.
Exam...
How to properly check if std::function is empty in C++11?
... an empty lambda doesn't really make sense. Behind the scenes the compiler converts a lambda expression into a struct (or class) definition, with the variables you capture stored as data members of this struct. A public function call operator is also defined, which is what allows you to invoke the l...
Difference between passing array and array pointer into function in C
...tialize an array, an expression that has type ‘‘array of type’’ is
converted to an expression with type ‘‘pointer to type’’ that points to the initial element of
the array object and is not an lvalue. If the array object has register storage class, the
behavior is undefined.
Given ...
The import android.support cannot be resolved
...Libraries tab. There click the Add External JARs Button on the Right pane.
Select the android-support-v4.jar file, usually the path for the Jar file is :
YOUR_DRIVE\android-sdks\extras\android\support\v4\android-support-v4.jar
After adding android-support-v4.jar Library, navigate to the Order and E...
Make xargs execute the command once for each line of input
...: space.txt: No such file or directory
A better solution is to use tr to convert newlines to null (\0) characters, and then use the xargs -0 argument. Here's an example:
echo "file with space.txt" | tr '\n' '\0' | xargs -0 ls
file with space.txt
If you then need to limit the number of calls yo...
Select unique or distinct values from a list in UNIX shell script
I have a ksh script that returns a long list of values, newline separated, and I want to see only the unique/distinct values. It is possible to do this?
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JavaScript: how to change form action attribute value based on selection?
I'm trying to change the form action based on the selected value from a dropdown menu.
5 Answers
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