newrockm

iter_bug/fib.py

@@ -12,5 +12,5 @@ def __iter__(self):
 
     def next(self):
         next_fib = self.last_1 + self.last_2
-        self.last_1, self.last2 = self.last_2, next_fib
+        self.last_1, self.last_2 = self.last_2, next_fib
         return next_fib

iter_bug/test.py

@@ -11,7 +11,7 @@ def test2():
     i.next()
     assert i.next() == 3
 
-def test2():
+def test3():
     f = fib.fib()
     i = iter(f)
     i.next()

sieve_gen/example.py

@@ -0,0 +1,10 @@
+import sieve
+
+count = 1
+
+for n in sieve.primes():
+    print n
+    count += 1
+    if count > 10:
+        break
+

sieve_gen/sieve.py

@@ -0,0 +1,22 @@
+# an implementation of Eratosthenes' Sieve as a generator
+
+def _is_prime(primes, n):
+    for i in primes:
+        if n % i == 0:
+            return False
+    return True
+
+def primes():
+    # first iteration, return 2 as the first prime number
+    primeslist = [2]
+    yield 2
+
+    # subsequent iterations build off of previously determined primes
+    start = primeslist[-1] + 1
+    while 1:
+        if _is_prime(primeslist, start):
+            primeslist.append(start)
+            yield start
+
+        start += 1
+

sieve_gen/test1.py

@@ -0,0 +1,6 @@
+import sieve
+
+# test 1 - the first prime should be 2
+gen = sieve.primes()
+assert gen.next() == 2
+

sieve_gen/test2.py

@@ -0,0 +1,9 @@
+import sieve
+
+# test 2 - the fourth prime should be 7 - happy :)
+gen = sieve.primes()
+gen.next()
+gen.next()
+gen.next()
+assert gen.next() == 7
+

sieve_gen/test3.py

@@ -0,0 +1,10 @@
+import sieve
+
+# test 3 - there are 10 primes less than 30
+count = 0
+gen = sieve.primes()
+while gen.next() < 30:
+    count += 1
+
+assert count == 10
+

sieve_iter/example.py

@@ -0,0 +1,10 @@
+import sieve
+
+count = 1
+
+for n in sieve.primes():
+    print n
+    count += 1
+    if count > 10:
+        break
+

sieve_iter/sieve.py

@@ -0,0 +1,27 @@
+# an implementation of Eratosthenes' Sieve as an iterator
+
+class primes(object):
+    def __init__(self):
+        self.primeslist = []
+
+    def __iter__(self):
+        return self
+
+    def _is_prime(self, n):
+        for i in self.primeslist:
+            if n % i == 0:
+                return False
+        return True
+
+    def next(self):
+        if len(self.primeslist) == 0:
+            self.primeslist.append(2)
+            return 2
+
+        self.start = self.primeslist[-1] + 1
+        while 1:
+            if self._is_prime(self.start):
+                self.primeslist.append(self.start)
+                return self.start
+            self.start += 1
+

sieve_iter/test1.py

@@ -0,0 +1,6 @@
+import sieve
+
+# test 1 - the first prime should be 2
+gen = sieve.primes()
+assert gen.next() == 2
+

sieve_iter/test2.py

@@ -0,0 +1,9 @@
+import sieve
+
+# test 2 - the fourth prime should be 7 - happy :)
+gen = sieve.primes()
+gen.next()
+gen.next()
+gen.next()
+assert gen.next() == 7
+

sieve_iter/test3.py

@@ -0,0 +1,10 @@
+import sieve
+
+# test 3 - there are 10 primes less than 30
+count = 0
+gen = sieve.primes()
+while gen.next() < 30:
+    count += 1
+
+assert count == 10
+

sieve_mod/example.py

@@ -0,0 +1,5 @@
+import sieve
+
+for n in range(10):
+    print sieve.next()
+

sieve_mod/sieve.py

@@ -0,0 +1,25 @@
+# an implementation of Eratosthenes' Sieve in a module
+
+_primeslist = []
+
+def _is_prime(primes, n):
+    for i in primes:
+        if n % i == 0:
+            return False
+    return True
+
+def next():
+    # first iteration, add 2 as a prime number
+    if len(_primeslist) == 0:
+        _primeslist.append(2)
+        return 2
+
+    # subsequent iterations build off of the previously determined list
+    start = _primeslist[-1] + 1
+    while 1:
+        if _is_prime(_primeslist, start):
+            _primeslist.append(start)
+            return start
+
+        start += 1
+