From b602a0ce3526c0d5f5fd6c681d6a70101a492d89 Mon Sep 17 00:00:00 2001
From: bnewbold <bnewbold@robocracy.org>
Date: Fri, 16 May 2014 01:44:16 -0400
Subject: hw01 assignment and julia notes

---
 assignments/hw01/question2_to_8.jl | 87 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 87 insertions(+)
 create mode 100644 assignments/hw01/question2_to_8.jl

(limited to 'assignments/hw01/question2_to_8.jl')

diff --git a/assignments/hw01/question2_to_8.jl b/assignments/hw01/question2_to_8.jl
new file mode 100644
index 0000000..3cf9dc9
--- /dev/null
+++ b/assignments/hw01/question2_to_8.jl
@@ -0,0 +1,87 @@
+
+using MAT
+
+all_vars= matread("sampledata2.mat")
+d = all_vars["data"]
+
+# ----------------------- Q2
+length(filter(x -> x > 5, d[:, 2])) / length(d[:, 2])
+# 0.19, so first statement is false
+
+length(filter(x -> x > 50, d[:, 1]))
+# 56x over 50
+
+length(filter(x -> x < 20, d[:, 1]))
+# 4x under 20
+# second statement is true
+
+length(filter(x -> x < 5, d[:, 2]))
+# 243
+length(filter(x -> x > 6, d[:, 2]))
+# 34
+# third statement is false
+
+length(filter(x -> x > 0.5, d[:, 3])) / length(d[:, 3])
+# 0.5233333333333333
+# last statement is false
+
+# ----------------------- Q3
+
+using Winston
+
+# TODO: this foldl business is ugly
+with_cancer = foldl(vcat, filter(x -> x[3] > 0.5, [d[row, :] for row = 1:size(d,1)]))
+without_cancer = foldl(vcat, filter(x -> x[3] < 0.5, [d[row, :] for row = 1:size(d,1)]))
+
+figure()
+p = FramedPlot()
+add(p, Histogram(hist(with_cancer[:, 1], 15:10:75)..., color="red"))
+
+# 1 NO (this is "without")
+# 2 yes
+# 3 NO
+# 4 NO
+
+# ----------------------- Q4
+
+add(p, Histogram(hist(without_cancer[:, 1], 15:10:75)..., color="green"))
+# 1 YES
+
+# ----------------------- Q5
+
+function fractional(f, d)
+    return length(filter(f, d)) / length(d)
+end
+
+fractional(x -> x>55, without_cancer[:, 1])
+#0.013986013986013986
+
+fractional(x -> x<25, without_cancer[:, 1])
+#0.08391608391608392
+# FALSE
+
+fractional(x -> x<35, without_cancer[:, 1])
+# FALSE
+
+fractional(x -> x<30, with_cancer[:, 1]) / fractional(x -> x>60, with_cancer[:, 1])
+# TRUE!
+
+fractional(x -> x>45, with_cancer[:, 1])
+# FALSE
+
+# ----------------------- Q6
+
+fractional(x -> x>35, with_cancer[:, 1])
+# 0.802547770700637
+
+# ----------------------- Q7
+
+fractional(x -> x<25, d[:, 1])
+# 0.06
+
+# ----------------------- Q8
+
+drinkers = foldl(vcat, filter(x -> x[2] > 3, [d[row, :] for row = 1:size(d,1)]))
+fractional(x -> x >0.5, drinkers[:, 3])
+# 0.6459627329192547
+
-- 
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