def testInterp(self):
xs = [1, 2, 3]
ys = [4, 5, 6]
interp = thinkstats.Interpolator(xs, ys)
y = interp.Lookup(1)
self.assertAlmostEqual(y, 4)
y = interp.Lookup(2)
self.assertAlmostEqual(y, 5)
y = interp.Lookup(3)
self.assertAlmostEqual(y, 6)
y = interp.Lookup(1.5)
self.assertAlmostEqual(y, 4.5)
y = interp.Lookup(2.75)
self.assertAlmostEqual(y, 5.75)
x = interp.Reverse(4)
self.assertAlmostEqual(x, 1)
x = interp.Reverse(6)
self.assertAlmostEqual(x, 3)
x = interp.Reverse(4.5)
self.assertAlmostEqual(x, 1.5)
x = interp.Reverse(5.75)
self.assertAlmostEqual(x, 2.75)
def ReadScale(filename='sat_scale.csv', col=2):
"""Reads a CSV file of SAT scales (maps from raw score to standard score).
Args:
filename: string filename
col: which column to start with (0=Reading, 2=Math, 4=Writing)
Returns:
list of (raw score, standardize score) pairs
"""
def ParseRange(s):
t = [int(x) for x in s.split('-')]
return 1.0 * sum(t) / len(t)
fp = open(filename)
reader = csv.reader(fp)
raws = []
scores = []
for t in reader:
try:
raw = int(t[col])
raws.append(raw)
score = ParseRange(t[col + 1])
scores.append(score)
except:
pass
raws.sort()
scores.sort()
return thinkstats.Interpolator(raws, scores)