What is the meaning of the dollar sign “$” in R function()?

The $ allows you extract elements by name from a named list. For example

x <- list(a=1, b=2, c=3)
x$b
# [1] 2

You can find the names of a list using names()

names(x)
# [1] "a" "b" "c"

This is a basic extraction operator. You can view the corresponding help page by typing ?Extract in R.

Related Posts:

  1. R Hex to RGB converter
  2. Define a global variable in a JavaScript function
  3. Define a global variable in a JavaScript function
  4. Counting the number of elements with the values of x in a vector
  5. Non-numeric Argument to Binary Operator Error in R
  6. Error in ggplot.data.frame : Mapping should be created with aes or aes_string
  7. Error in file(file, “rt”) : invalid ‘description’ argument in complete.cases program
  8. SummarySE (Rmisc package) to produce a barplot with error bars (ggplot2)
  9. Editing legend (text) labels in ggplot
  10. Logistic Regression on factor: Error in eval(family$initialize) : y values must be 0 <= y <= 1
  11. R – longer object length is not a multiple of shorter object length
  12. Error: attempt to use zero-length variable name
  13. “non-numeric argument to binary operator” error in R
  14. Replace all particular values in a data frame
  15. How can I convert Json to data frame in R
  16. Error in xj[i] : invalid subscript type ‘list’
  17. How do you specifically order ggplot2 x axis instead of alphabetical order?
  18. Error: Invalid number of ‘breaks’ in R
  19. Sample random rows in dataframe
  20. Batch convert columns to numeric type
  21. Deleting rows that are duplicated in one column based on the conditions of another column
  22. Replace all 0 values to NA
  23. How can I change the name of a data frame
  24. In R, dealing with Error: ggplot2 doesn’t know how to deal with data of class numeric
  25. Error in plot.new() : figure margins too large, Scatter plot
  26. Reasons for using the set.seed function
  27. Error in do_one(nmeth) : NA/NaN/Inf in foreign function call (arg 1)
  28. What is the proper declaration of main in C++?
  29. Non-numeric Argument to Binary Operator Error in R
  30. What are the “standard unambiguous date” formats for string-to-date conversion in R?
  31. R issue “object not found”
  32. How do I delete rows in a data frame?
  33. Error in grid.Call(L_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : Polygon edge not found
  34. Remove duplicated rows
  35. What is lexical scope?
  36. Error in file(file, “rt”) : invalid ‘description’ argument in complete.cases program
  37. Error: Incorrect number of dimensions in R
  38. Error in lm.fit(x, y, offset = offset, singular.ok = singular.ok, …) : NA/NaN/Inf in ‘y’, tried every possible way
  39. remove legend title in ggplot
  40. “replace” function examples
  41. Why I get this error writing data to a file
  42. C error: undefined reference to function, but it IS defined
  43. Error in lis[[i]] : attempt to select less than one element
  44. How to compute weighted mean in R?
  45. Subscript out of bounds – general definition and solution?
  46. R: Error in eval(predvars, data, env) : numeric ‘envir’ arg not of length one in intrinsic.pars() in multgee package
  47. Correlation between multiple variables of a data frame
  48. Remove all of x axis labels in ggplot
  49. How can I plot data with confidence intervals?
  50. Unimplemented type list when trying to write.table
  51. How to use Global Variables in C#?
  52. How to convert a factor to integer\numeric without loss of information?
  53. Don’t understand why UnboundLocalError occurs (closure) [duplicate]
  54. predict.lm() in a loop. warning: prediction from a rank-deficient fit may be misleading
  55. Why is my HelloWorld function not declared in this scope?
  56. reshape2 melt warning message
  57. error: “initializer expression list treated as compound expression”
  58. How to sum a variable by group
  59. grep using a character vector with multiple patterns
  60. dcast warning: ‘Aggregation function missing: defaulting to length’
  61. remove all variables except functions
  62. Getting error: ISO C++ forbids declaration of with no type
  63. Combine two data frames by rows (rbind) when they have different sets of columns
  64. How to stop a function
  65. How do I install an R package from source?
  66. Optimization of a function in R ( L-BFGS-B needs finite values of ‘fn’)
  67. `Error in file(con, “r”) : cannot open the connection` from running BRugsFit()
  68. includes() not working in all browsers
  69. Anagrams finder in javascript
  70. Python: Can a function return an array and a variable?
  71. Php include not working? function not being included
  72. What does it mean that “a declaration shadows a parameter”?
  73. ‘Incomplete final line’ warning when trying to read a .csv file into R
  74. R error: “New Column would leave holes after existing columns”
  75. How do I combine two data-frames based on two columns?
  76. Convert R code into Python code using rpy2
  77. How to return a boolean method in java?
  78. What is define([ , function ]) in JavaScript?
  79. Why can’t we pass arrays to function by value?
  80. How to catch integer(0)?
  81. Indicator function in R
  82. r random forest error – type of predictors in new data do not match
  83. env=baseenv() in R
  84. Stopping a JavaScript function when a certain condition is met
  85. R4DS error comparison (1) is possible only for atomic and list types
  86. Optional arguments in C function
  87. How do I pass the this context to a function?
  88. R Sweave: NO TeX installation detected
  89. Passing string to a function in C – with or without pointers?
  90. Suppress output of a function
  91. Is there a math nCr function in python? [duplicate]
  92. Remove columns from dataframe where some of values are NA
  93. Colour points in a plot differently depending on a vector of values
  94. Difference between function arguments declared with & and * in C++
  95. Use of ~ (tilde) in R programming Language
  96. Is C++ Array passed by reference or by pointer?
  97. “cannot be used as a function error”
  98. How to run a PHP function from an HTML form?
  99. Filter rows which contain a certain string
  100. Write a program that asks the user to enter five test scores. Correspond it to a letter grade

Leave a Comment