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What's the fastest way to merge/join data.frames in R?
...he first. If there are duplicates in the second data frame then the match and merge approaches are not the same. Match is, of course, faster since it is not doing as much. In particular it never looks for duplicate keys. (continued after code)
DF1 = data.frame(a = c(1, 1, 2, 2), b = 1:4)
DF2 = da...
Adding a column to a data.frame
...xt, [[.data.frame.
Data frames can be indexed in several modes. When [ and [[ are used with a single vector index (x[i] or x[[i]]), they index the data frame as if it were a list.
my.dataframe["new.col"] <- a.vector
my.dataframe[["new.col"]] <- a.vector
The data.frame method for $, ...
How to detect if a script is being sourced
...
This seems to be portable between Bash and Korn:
[[ $_ != $0 ]] && echo "Script is being sourced" || echo "Script is a subshell"
A line similar to this or an assignment like pathname="$_" (with a later test and action) must be on the first line of the s...
Could not load file or assembly 'Newtonsoft.Json' or one of its dependencies. Manifest definition do
...ensured all my projects used the same version by running the following command and checking the results:
update-package Newtonsoft.Json -reinstall
And, lastly I removed the following from my web.config:
<dependentAssembly>
<assemblyIdentity name="Newtonsoft.Json" publicKeyToken="3...
Generate colors between red and green for a power meter?
I'm writing a Java game and I want to implement a power meter for how hard you are going to shoot something.
19 Answers
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PHP Regex to check date is in YYYY-MM-DD format
...t answer? This returns true for a number of invalid dates like 2016-02-30 and 2016-09-31
– Graham
Oct 11 '16 at 14:35
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How to convert floats to human-readable fractions?
...y what you are asking for. Its based on the theory of continued fractions and very fast and fairly compact.
I have used versions of this customized for specific numerator and denominator limits.
/*
** find rational approximation to given real number
** David Eppstein / UC Irvine / 8 Aug 1993
**
*...
How to compare software version number using js? (only number)
... would be to use Array.split to get arrays of parts from the input strings and then compare pairs of parts from the two arrays; if the parts are not equal we know which version is smaller.
There are a few of important details to keep in mind:
How should the parts in each pair be compared? The que...
Fastest way to determine if an integer's square root is an integer
... ~35% faster than your 6bits+Carmack+sqrt code, at least with my CPU (x86) and programming language (C/C++). Your results may vary, especially because I don't know how the Java factor will play out.
My approach is threefold:
First, filter out obvious answers. This includes negative numbers and ...
How to test which port MySQL is running on and whether it can be connected to?
I have installed MySQL and even logged in there as a user.
13 Answers
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