Assignment 13 - Optional: Writing a function - Conditional Statement

How to do it?:

• Open the Rmarkdown file of this assignment (link) in Rstudio.

• Right under each question, insert a code chunk (you can use the hotkey Ctrl + Alt + I to add a code chunk) and code the solution for the question.

• Knit the rmarkdown file (hotkey: Ctrl + Alt + K) to export an html.

• Publish the html file to your Githiub Page.

Submission: Submit the link on Github of the assignment to Canvas

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NOTICE: Question 7, 8 and 9 are optional.

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1. Write a function to calculate the age of a person. Give an example to test your function.

• Input: a number, x, (year born)

• Output: Print out “You are r age”. Where r is the age of the person, i.e. 2020 - x.

Hint: Similar Function

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2. Write the following function. Give an example to test your function.

• Input: a number

• Output: print out: “You input an even number!” if the number is event, or “You input an odd number!” otherwise.

Hint: Similar Function

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3. Write the following function. Give an example to test your function.

• Input: a numeric vector

• Output:

  • if the input vector has missing values: return the input vector with missing values replaced by mean

  • if the input vector has no missing value: return the same input vector

Hint: Similar Function

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4. Write the following function. Give an example to test your function.

• Input: a vector x

• Output: The vector x where the missing values replaced by the mean (if x is numeric) or the mode (if x is non-numeric). If x does not have missing value, return the same vector x.

Hint: Use If-statement to combine the function in Question 3 and this function

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5. Write the following function. Give examples to test your function.

• Input: A data frame of two variables x and y

• Output:

  • A boxplot of x by y if x is numeric and y is non-numeric

  • A boxplot of y by x if y is numeric and x is non-numeric

  • print out ‘This function cannot visualize your data’ otherwise

Hint:

• Similar Function

• You can refer to this slide to plot a boxplot: https://bryantstats.github.io/math421/slides/6_viz.html#36

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6. Combine the function in Question 5 and the function in this example (Link) to have a function that can plot all possible cases (2 categorical, 2 numeric, 1 numeric and 1 categorical).

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NOTICE: Question 7, 8 and 9 are optional.

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7. Write the following function. Give examples to test your function.

• Input:

  • input_data: a clean data frame with a variable name target. The target variable is also binary.

  • train_percent: a number presenting a proportion of training data. The default train_percent is .8

• Output: the accuracy of the decision model rpart where the training data is train_percent.

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8. Write the following function. Give examples to test your function.

• Input:

  • input_data: a clean data frame with a variable name target. The target variable is also binary.

  • train_percent: a number presenting a proportion of training data. The default train_percent is .8

• Output: the plot of variable important by random forest trained by caret.

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9. Write the following function. Give examples to test your function.

• Input:

  • a data frame that has a text column

  • the name of the text column in the data

• Output: the word cloud plot of the text column

Sample codes

• Word Cloud codes

• A similar function