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Questions tagged [r-faq]

The r-faq tag is created to group a limited number of questions discussing problems that come up regularly on the R tag. It is not the official FAQ on R for SO, but should serve as an interesting source of information on common problems.

The tag is created to group a limited number of questions discussing problems that come up regularly on the tag. It is not the official FAQ on R for SO, but should serve as an interesting source of information on common problems.

The "real" original R-FAQ is reliably found at: https://cran.r-project.org/doc/FAQ/R-FAQ.html and is typically the first google hit for "r-faq".

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Calculate group mean, sum, or other summary stats. and assign column to original data

I want to calculate mean (or any other summary statistics of length one, e.g. min, max, length, sum) of a numeric variable ("value") within each level of a grouping variable ("group"). The summary statistic should be assigned to a new variable which…
Mike
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What does "Error: object '' not found" mean?

I got the error message: Error: object 'x' not found Or a more complex version like Error in mean(x) : error in evaluating the argument 'x' in selecting a method for function 'mean': Error: object 'x' not found What does this mean?
Richie Cotton
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How to get help in R?

What is the possible documentation available for R package? For example I try to understand sp package. In addition to help(sp), what are the other functions for searching through help and documentation?
Tomas Greif
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Changing date format in R

I have some very simple data in R that needs to have its date format changed: date midpoint 1 31/08/2011 0.8378 2 31/07/2011 0.8457 3 30/06/2011 0.8147 4 31/05/2011 0.7970 5 30/04/2011 0.7877 6 31/03/2011 0.7411 7 …
indigo
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Error in : target of assignment expands to non-language object

I received the error Error in : target of assignment expands to non-language object or Error in : invalid (do_set) left-hand side to assignment or Error in : invalid (NULL) left side of assignment What does it mean,…
Richie Cotton
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FAQ markup to R data structure

I'm reading the R FAQ source in texinfo, and thinking that it would be easier to manage and extend if it was parsed as an R structure. There are several existing examples related to this: the fortunes package bibtex entries Rd files each with some…
baptiste
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Why can't I get a p-value smaller than 2.2e-16?

I've found this issue with t-tests and chi-squared in R but I assume this issue applies generally to other tests. If I do: a <- 1:10 b <- 100:110 t.test(a,b) I get: t = -64.6472, df = 18.998, p-value < 2.2e-16. I know from the comments that…
arandomlypickedname
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How to end a 'debug' mode?

In RStudio, I started a debug mode by debug(ls) ls() Then I do not know how to end this mode. The prompt changed to Browse[2]> How can I end this debugging mode?
user67275
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How to find all functions in an R package?

What is the best way to find all the functions associated in a package?? I am currently going through the caTools package. If I do ?caTools or ??caTools I am simply going to get search for functions called that but not the functions in the package.…
jessica
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How to get mean, median, and other statistics over entire matrix, array or dataframe?

I know this is a basic question but for some strange reason I am unable to find an answer. How should I apply basic statistical functions like mean, median, etc. over entire array, matrix or dataframe to get unique answers and not a vector over rows…
user2760
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Dealing with TRUE, FALSE, NA and NaN

Here is a vector a <- c(TRUE, FALSE, FALSE, NA, FALSE, TRUE, NA, FALSE, TRUE) I'd like a simple function that returns TRUE everytime there is a TRUE in "a", and FALSE everytime there is a FALSE or a NA in "a". The three following things do not…
Remi.b
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What are the differences between concatenating strings with cat() and paste()?

What are the differences between concatenating strings with cat and paste? In particular, I have the following questions. Why does R not use the double quote (") when it prints the results of calling cat (but it uses quotes when using paste)? >…
Sam
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dplyr left_join by less than, greater than condition

This question is somewhat related to issues Efficiently merging two data frames on a non-trivial criteria and Checking if date is between two dates in r. And the one I have posted here requesting if the feature exist: GitHub issue I am looking to…
rajvijay
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Subset data frame based on number of rows per group

I have data like this, where some "name" occurs more than three times: df <- data.frame(name = c("a", "a", "a", "b", "b", "c", "c", "c", "c"), x = 1:9) name x 1 a 1 2 a 2 3 a 3 4 b 4 5 b 5 6 c 6 7 c 7 8 c 8 9 c 9 I…
SJSU2013
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How can I remove all duplicates so that NONE are left in a data frame?

There is a similar question for PHP, but I'm working with R and am unable to translate the solution to my problem. I have this data frame with 10 rows and 50 columns, where some of the rows are absolutely identical. If I use unique on it, I get one…
Lilith-Elina
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