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Split delimited strings in a column and insert as new rows [duplicate]
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As of Dec 2014, this can be done using the unnest function from Hadley Wickham's tidyr package (see release notes http://blog.rstudio.org/2014/12/08/tidyr-0-2-0/)
> library(tidyr)
> library(dplyr)
> mydf
V1 V2
2 1 a,b,c
3 2 a,c
4 3 b,d
5 4 e,f
6 . .
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Why is Java's Iterator not an Iterable?
...instance in a collection. Iterable implies that one may obtain an iterator from an object to traverse over its elements - and there's no need to iterate over a single instance, which is what an iterator represents.
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Why do we need the “event” keyword while defining events?
... contained in it. The -= and += operators can still be invoked on an event from outside the class defining it (they get the access modifier you wrote next to the event).
You can also override the way -= and += behave on events.
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Regex doesn't work in String.matches()
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What do you mean by other languages followed suit? From what I know, only C++ has an equivalent set of methods - regex_search and regex_match. In Python, re.match only anchors the match at the start of the string (as if it were \Apattern) and Python 3.x has got a nice .fullma...
Should a function have only one return statement?
...urn;
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}
So yes, I think it's fine to have multiple "exit points" from a function/method.
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edited Mar 11 '15 at 20:40
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How to delete all the rows in a table using Eloquent?
...his works for Laravel 4 and 5:
MyModel::truncate();
That drops all rows from the table without logging individual row deletions.
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Why can't I call read() twice on an open file?
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With Python3, use pathlib. from pathlib import Path; text = Path(filename).read_text() Takes care of open, close, etc.
– PaulMcG
Jun 19 '17 at 12:06
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What is the purpose of the Visual Studio Hosting Process?
... The hosting process tends to keep DLLs loaded that I want to write to from another running copy of Visual Studio. Killing the hosting process, or even exiting and restarting the offending VS, does not help, because the newly started hosting process loads the DLL again. This is the reason why I ...
np.mean() vs np.average() in Python NumPy?
...n some cases. I have a very large single-precision array that is accessed from an h5 file. If I take the mean along axes 0 and 1, I get wildly incorrect results unless I specify dtype='float64':
>T.shape
(4096, 4096, 720)
>T.dtype
dtype('<f4')
m1 = np.average(T, axis=(0,1)) ...
How to convert a String to CharSequence?
... explaining that a String IS a CharSequence. Then poster answers how to go from CharSequence to String.
– Alex A.
Nov 8 '13 at 23:05
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