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Omit rows containing specific column of NA
...# 2 2 10 33
EDIT: Only return rows with no NAs
If you want to eliminate all rows with at least one NA in any column, just use the complete.cases function straight up:
DF[complete.cases(DF), ]
# x y z
# 2 2 10 33
Or if completeFun is already ingrained in your workflow ;)
completeFun(DF, na...
Fastest way to check if a file exist using standard C++/C++11/C?
...e thousands of files and before doing something on them I need to check if all of them exist. What can I write instead of /* SOMETHING */ in the following function?
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Setting the filter to an OpenFileDialog to allow the typical image formats?
I have this code, how can I allow it to accept all typical image formats? PNG, JPEG, JPG, GIF?
11 Answers
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How can I get a count of the total number of digits in a number?
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@Puterdo Borato: my performance test actually showed that your method is faster when the number of digits are < 5. Pass that, Steve's Math.floor is faster.
– stack247
Apr 7 '15 at 22:56
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Why does ~True result in -2?
...00000001
and ~1 is:
11111110
Which is -2 in Two's complement1
1 Flip all the bits, add 1 to the resulting number and interpret the result as a binary representation of the magnitude and add a negative sign (since the number begins with 1):
11111110 → 00000001 → 00000010
↑ ...
How to check if multiple array keys exists
... check (like in the original question), it's probably easy enough to just call array_key_exists() twice to check if the keys exists.
if (array_key_exists("story", $arr) && array_key_exists("message", $arr)) {
// Both keys exist.
}
However this obviously doesn't scale up well to many k...
Difference between Observer, Pub/Sub, and Data Binding
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Here's my take on the three:
Data Binding
Essentially, at the core this just means "the value of property X on object Y is semantically bound to the value of property A on object B. No assumptions are made as to how Y knows or is fed changes on object B.
Observer, or Obser...
how to disable DIV element and everything inside [duplicate]
I need to disable a DIV and all it's content using Javascript. I can swear that doing a simple
5 Answers
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What is the behavior difference between return-path, reply-to and from?
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Now, let's describe the different "FROM"s.
The return path (sometimes called the reverse path, envelope sender, or envelope from — all of these terms can be used interchangeably) is the value used in the SMTP session in the MAIL FROM command. As you can see, this does not need to be the same v...
What's the fastest way to merge/join data.frames in R?
...(y) from main.d group by g1, g2"))
)
The outputs from the two benchmark call comparing the merge calculations are:
Joining by: x
test replications elapsed relative user.self sys.self user.child sys.child
3 data.table 1 0.34 1.000000 0.31 0.01 NA NA
2 ...