2020年5月1日 · \1 is equivalent to re.search(...).group(1), the first parentheses-delimited expression inside of the regex. It's also, fun fact, part of the reason that regular expressions are significantly slower in Python and other programming languages than required to be by CS theory.

2022年1月11日 · R provides two different methods for accessing the elements of a list or data.frame: [] and [[]]. What is the difference between the two, and when should I use one over the other?

2014年11月25日 · The funny percent-sign syntax is how R lets users define their own infix functions. An example of a built-in infix operator in R is +; the + in 1 + 2 actually does the function call `+`(1, 2) (you can see this by looking at the source code by typing in `+`).

2009年11月27日 · Back-references to condition patterns are identified by {C:N} where N is from 0 to 9; back-references to rule pattern are identified by {R:N} where N is from 0 to 9.

2011年8月10日 · I often seen the symbol 1L (or 2L, 3L, etc) appear in R code. Whats the difference between 1L and 1? 1==1L evaluates to TRUE. Why is 1L used in R code?

2010年6月8日 · How do I generate a vector with a specified increment step (e.g. 2)? For example, how do I produce the following 0 2 4 6 8 10

2012年2月4日 · I use print to output from a function in R, for example: print ("blah blah blah") This outputs [1] "blah blah blah" To the console. How can I avoid the [1] and the quotes?

I have a number, for example 1.128347132904321674821 that I would like to show as only two decimal places when output to screen (or written to a file). How does one do that? x <- 1.

2015年11月26日 · Then by running that: df * 1 all Falses and Trues are trasnformed into 1s and 0s. At least, this was happen in the R version that I have (R version 3.4.4 (2018-03-15) ).

2012年7月13日 · Possible Duplicate: How to generate a vector containing a numeric sequence? In R, how can I get the list of numbers from 1 to 100? Other languages have a function 'range' to do this. R's range...