R Online Test

The data science team in a telecom company needs an R function that will load a CSV file into a DataFrame and format it so that it can be used with already existing R code.

The loadData function accepts a path to a file or a textConnection that points to a CSV file. The CSV file doesn't contain headers and has two columns, the first is a decimal number and the second one is a string. The first column represents an id and the second column represents a color. Some rows in the CSV file contain "0" instead of "yellow" in the second column.

The function should return a DataFrame after:

• loading data from the CSV into the DataFrame.
• replacing all "0" in the second column with "yellow".
• renaming the first column to "id" and the second column to "color".

For example, the following code:

text = "0.0,blue\n1.0,0\n2.0,red"
print(loadData(text))

Should print:

  id  color
1  0   blue
2  1 yellow
3  2    red

A company stores login data and passwords in two different containers:

• A DataFrame with the columns: id, name, and verified.
• A matrix where each row contains, in order: id and password.

The first column of any row in the matrix corresponds to the id column in the DataFrame. Elements on the same row/index in both the DataFrame and the matrix have the same id.

Implement the function loginTable that accepts these two containers and returns a new DataFrame that contains the following columns:

• The id column from the idNameVerified DataFrame.
• The name column from the idNameVerified DataFrame.
• A new column, called password that contains the password from the idPassword matrix.

For example, the following code snippet:

idNameVerified = data.frame(id = c(1, 2), 
    name = c("JohnDoe", "AnnFranklin"),
    verified = c(TRUE, FALSE))
idPassword = matrix(c(1, 2, 987340123, 187031122),
    nrow=2,
    ncol=2)

print(loginTable(idNameVerified,idPassword))

Should print:

  id        name  password
1  1     JohnDoe 987340123
2  2 AnnFranklin 187031122