The h table records addresses within San Diego. Only 50
+addresses are recorded. The index of the dataframe contains the numbers
+1-50 as unique integers.
"number" (int): Street address number"street" (str): Street nameThe o table records information on power outages within
+San Diego in April 2024. Only 100 outages are recorded. The index of the
+dataframe contains the numbers 1-100 as unique integers.
"time" (pd.Timestamp): When the outage began"duration" (int): How long the outage lasted in
+minutes
The j table is a table that links outages to addresses.
+Each entry in the j table contains the hid of
+the affected address and the oid of the outage. For
+example, the first row of the table records that the outage with an
+oid of 1 caused the power to go out at addresses with
+hid 61 and 88. A single outage can affect multiple
+addresses. There are no missing values and no duplicated rows in this
+table, and all values are positive integers. This table records all the
+addresses affected by all of the outages in 2024 so far.
"hid" (int): The hid of the affected
+address"oid" (int): The oid of the outage
Fill in Python code below so that the last line of each part
evaluates to each desired result using the tables h,
@@ -328,41 +361,107 @@
h, j, and o, then
perform the join by hand. For example, consider the following example
h, j, and o tables:
-| hid | +
|---|
| 1 | +
| 2 | +
| 3 | +
| hid | +oid | +
|---|---|
| 1 | +1 | +
| 2 | +1 | +
| 2 | +10 | +
| 2 | +11 | +
| 10 | +3 | +
| 11 | +3 | +
| oid | +
|---|
| 1 | +
| 2 | +
| 3 | +
In this example, whoa would look like the following
(omitting other columns besides hid and oid
for brevity):
| hid | +oid | +
|---|---|
| 1 | +1 | +
| 2 | +1 | +
| NaN | +2 | +
| NaN | +3 | +
There are 3 cases where rows will be kept for whoa:
hid and oid match in the three
diff --git a/pages/exams/sp24-midterm.yml b/pages/exams/sp24-midterm.yml
index 27dbb80..74be09a 100644
--- a/pages/exams/sp24-midterm.yml
+++ b/pages/exams/sp24-midterm.yml
@@ -2,6 +2,7 @@ title: 'Spring 2024 Midterm Exam'
instructors: Sam Lau
context: This exam was administered in-person. The exam was closed-notes, except students were allowed to bring a single two-sided notes sheet. No calculators were allowed. Students had **80 minutes** to take this exam.
show_solution: true
+data_info: sp24-midterm/sp24-midterm-data-info
problems:
- sp24-midterm/sp24-mid-q01
- sp24-midterm/sp24-mid-q02
diff --git a/problems/sp24-midterm/sp24-mid-q02.md b/problems/sp24-midterm/sp24-mid-q02.md
index be5a825..b026280 100644
--- a/problems/sp24-midterm/sp24-mid-q02.md
+++ b/problems/sp24-midterm/sp24-mid-q02.md
@@ -40,15 +40,14 @@ Write a **single expression** that evaluates to the number of rows in `whoa`. In
We know that `h` has the numbers 1-50 as unique integers in its index, and `o` has the numbers 1-100 as unique integers in its index. However, the `hid` and `oid` columns in `j` have values outside these ranges. To approach this problem, it's easiest to come up with smaller versions of `h`, `j`, and `o`, then perform the join by hand. For example, consider the following example `h`, `j`, and `o` tables:
-