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Replacing NAs with latest non-NA value

In a data.frame (or data.table), I would like to "fill forward" NAs with the closest previous non-NA value. A simple example, using vectors (instead of a data.frame ) is the following: ...
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data.table vs dplyr: can one do something well the other can't or does poorly?

I'm relatively familiar with data.table , not so much with dplyr . I've read through some dplyr vignettes and examples that have popped up on SO, and so far my conclusions are that: ...
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Google Maps API 3 - Custom marker color for default (dot) marker

I've seen lots of other questions similar to this ( here , here and here ), but they all have accepted answers that don't solve my problem. The best solution I have found to the problem is the StyledMarker library, which does let you define custom colours for markers, but I can't get it to use ...
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Select n random rows from SQL Server table

I've got a SQL Server table with about 50,000 rows in it. I want to select about 5,000 of those rows at random. I've thought of a complicated way, creating a temp table with a "random number" column, copying my table into that, looping through the temp table and updating each row with RAND() , and ...
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Reflecting parameter name: abuse of C# lambda expressions or syntax brilliance?

I am looking at the MvcContrib Grid component and I'm fascinated, yet at the same time repulsed, by a syntactic trick used in the Grid syntax : ...
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How do you install Google frameworks (Play, Accounts, etc.) on a Genymotion virtual device? [duplica

I'm currently trying out Genymotion and boy, it's so much faster than the ADT emulator. 10 Answers ...
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Check whether user has a Chrome extension installed

I am in the process of building a Chrome extension, and for the whole thing to work the way I would like it to, I need an external JavaScript script to be able to detect if a user has my extension installed. ...
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Change app language programmatically in Android

Is it possible to change the language of an app programmatically while still using Android resources? 35 Answers ...
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How to estimate a programming task if you have no experience in it [closed]

I am having a difficult time with management asking for estimates on programming tasks that are using third-party controls that I have no prior experience with. ...
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Should I put #! (shebang) in Python scripts, and what form should it take?

Should I put the shebang in my Python scripts? In what form? 12 Answers 12 ...