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In R, the ________ function can be used to check if a value is numeric.

  • is.character()
  • is.factor()
  • is.logical()
  • is.numeric()
The is.numeric() function in R is used to check if a value is numeric. It returns TRUE if the value is numeric and FALSE otherwise.
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What would be the output if you try to print a variable that doesn't exist in R?

  • A blank output
  • An error message
  • The string "NA"
  • The string "NULL"
If you try to print a variable that doesn't exist in R, you will get an error message stating "Error: object 'x' not found", where 'x' is the name of the non-existent variable. This is because R tries to find the variable in the environment and fails when it does not exist.
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In R, the ________ function is used to calculate the natural logarithm of a number.

  • ln()
  • log()
  • log10()
  • natural_log()
The log() function in R is used to calculate the natural logarithm of a number. By default, it computes natural logarithms, but you can also provide a base as the second argument. For example, log(7) would return the natural logarithm of 7.
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In R, to access the first element of an array named myarray, you would use ______.

  • myarray[1]
  • myarray[[1]]
  • myarray[1, 1]
  • myarray[[1, 1]]
In R, to access the first element of an array named myarray, you would use myarray[1]. The square brackets [] are used to extract elements from an array. The index 1 refers to the first element of the array.
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To calculate the mean of each column in a data frame in R, you would use the ______ function.

  • colMeans()
  • rowMeans()
  • mean()
  • apply()
To calculate the mean of each column in a data frame in R, you would use the colMeans() function. The colMeans() function computes the mean values across each column of the data frame.
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You have a script that isn't running as expected, and you suspect there's an issue with the syntax.

  • Ask someone else to fix it
  • Delete the script and start over
  • Ignore the error and continue
  • Use the traceback() function
The 'traceback()' function in R prints out the function call stack after an error occurs. This can help identify where the error is in the code, especially for syntax errors. Other debugging tools in R include 'debug()', 'browser()', and 'recover()'.
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Suppose you're working with a list of vectors of different types and you need to concatenate them into a single vector. How would you approach this?

  • None of the above
  • Use the c() function
  • Use the paste() function
  • Use the unlist() function
If you're working with a list of vectors of different types and you need to concatenate them into a single vector, you can use the 'unlist()' function. This function can flatten a list of vectors into a single vector.
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Suppose you're asked to create a pie chart in R that shows the distribution of a categorical variable in a data set. How would you do it?

  • Use the pie() function and provide a vector of non-negative numeric values representing the proportions of the segments
  • Use the barplot() function and specify the categorical variable as the x argument
  • Use the plot() function with type = "pie" and specify the categorical variable as the data argument
  • Use the ggplot2 package and the geom_bar() function with the categorical variable as the x aesthetic
To create a pie chart in R that shows the distribution of a categorical variable in a data set, you would use the pie() function. Provide a vector of non-negative numeric values representing the proportions of the segments corresponding to each category.
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If you want to include a literal backtick in a string in R, you would use the escape sequence ________.

  • `
  • t
  • b
  • '
In R, to include a literal backtick in a string, you would use the escape sequence ' . For example, "This is a backtick: '" would result in the string This is a backtick: `.
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The ______ function in R can be used to find the index of the maximum value in a vector.

  • which.max()
  • which.min()
  • index.max()
  • index.min()
The which.max() function in R can be used to find the index of the maximum value in a vector. The which.max() function returns the index of the first occurrence of the maximum value.
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