Chapter 2 · Section 1 practice

DataFrame Foundations

0 of 6 answered

These questions review the examples in the companion slides. Choose an answer, then check the explanation.

Question 1

Which selection returns a Series from df?

  • df["AEP"]
  • df[["AEP"]]
  • df.loc[:, ["AEP"]]
  • df.head()

Question 2

A table has 5 rows and 3 numeric columns. How many values does df.mean(axis=0) return?

  • 5
  • 15
  • 1
  • 3

Question 3

After df.set_index("ticker"), how can ticker become a column again?

  • dropna()
  • mean()
  • reset_index()
  • sort_index()

Question 4

After sorting rows by price, what happens to their index values?

  • They remain in chronological order
  • Each index value stays with its original row
  • They are automatically replaced by 0, 1, 2
  • They are deleted

Question 5

Two numeric frames overlap on one row index value and two column names. Where can their sum have observed values?

  • At the two shared row/column combinations
  • At every cell in either frame
  • At no cells
  • Only at the first row position

Question 6

Ticker and date are already columns. Which export avoids an extra column for the incidental row index?

  • df.to_csv("prices.csv", index=True)
  • df.sort_index()
  • df.reset_index(drop=True)
  • df.to_csv("prices.csv", index=False)