Categorizing blood pressure

Use integer readings in millimeters of mercury (mm Hg).

Write a function that takes positive systolic and diastolic blood pressure readings as input and returns a category (Normal, Elevated, Hypertension Stage 1, Hypertension Stage 2, or Severe Hypertension) using if/elif/else statements. Apply the categories from highest to lowest and use the more severe category when either reading crosses its threshold. Raise ValueError if either reading is not positive.

Table 1: Blood pressure categories adapted from the American Heart Association’s current categories. A hypertensive emergency also depends on symptoms and cannot be diagnosed by this programming exercise.
Blood Pressure Category Systolic Range Diastolic Range
Normal Below 120 and below 80
Elevated 120–129 and below 80
Hypertension Stage 1 130–139 or 80–89
Hypertension Stage 2 140 and above or 90 and above
Severe Hypertension Above 180 and/or above 120

Complete Listing 1. Save the completed code as categorize_blood_pressure.py and run it to check the supplied assertions.

Listing 1: Starter function and checks for categorize_blood_pressure. 
def categorize_blood_pressure(systolic: int, diastolic: int) -> str:
    raise NotImplementedError("Replace this line with your code.")


# Inside a band
got = categorize_blood_pressure(110, 70)
assert got == "Normal", f"110/70: expected 'Normal', got {got!r}"

# At the bottom of the elevated band, and just below it
got = categorize_blood_pressure(120, 75)
assert got == "Elevated", f"120/75: expected 'Elevated', got {got!r}"

got = categorize_blood_pressure(119, 79)
assert got == "Normal", f"119/79: expected 'Normal', got {got!r}"

# The systolic reading is elevated, but the diastolic one is higher in rank
got = categorize_blood_pressure(125, 85)
assert got == "Hypertension Stage 1", f"125/85: expected 'Hypertension Stage 1', got {got!r}"

# Both readings sit in stage 2
got = categorize_blood_pressure(150, 95)
assert got == "Hypertension Stage 2", f"150/95: expected 'Hypertension Stage 2', got {got!r}"

# Above every threshold
got = categorize_blood_pressure(190, 130)
assert got == "Severe Hypertension", f"190/130: expected 'Severe Hypertension', got {got!r}"

# A reading that is not positive is invalid input, not a category
try:
    categorize_blood_pressure(0, 80)
    raise AssertionError("0/80: expected ValueError, but a category was returned")
except ValueError:
    pass

# Your case: which pair of readings is most likely to break it?
# got = categorize_blood_pressure(___, ___)
# assert got == "___", f"___: expected '___', got {got!r}"
  • assert condition checks a Boolean condition. A true condition produces no output; a false condition raises AssertionError. For example, assert 2 + 3 == 5 passes.