Chapter folders renamed

Chapter04/iterators/abc.txt

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+Iteration is one of the key tools used for data processing and data transformation.
+The iterations are especially useful when dealing with large datasets and bringing
+the whole dataset into the memory is not possible or efficient. Iterators provide
+a way to bring the data into memory one item at a time.

Chapter04/iterators/generator1.py

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+#generators1.py
+def my_gen():
+    yield 'A'
+    yield 'B'
+    yield 'C'
+
+
+if(__name__ == "__main__"):
+    iter1 = my_gen()
+    print(iter1.__next__())
+    print(next(iter1))
+    print(iter1.__next__())

Chapter04/iterators/generator2.py

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+#generator2.py
+class Week:
+    def __init__(self):
+        self.days = {1:'Monday', 2: "Tuesday",
+                     3:"Wednesday", 4: "Thursday",
+                     5:"Friday", 6:"Saturday", 7:"Sunday"}
+
+    def week_gen(self):
+        for x in self.days:
+            yield self.days[x]
+
+if(__name__ == "__main__"):
+    wk = Week()
+    iter1 = wk.week_gen()
+    iter2 = iter(wk.week_gen())
+    print(iter1.__next__())
+    print(iter2.__next__())
+    print(next(iter1))
+    print(next(iter2))

Chapter04/iterators/generator3.py

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+#generator3.py
+L = [1,2,3,4,5,6,7,8,9,0]
+f1 = [x+1 for x in L]
+g1 = (x+1 for x in L)
+
+print(g1.__next__())
+print(g1.__next__())

Chapter04/iterators/generator4.py

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+#generator4.py
+def prime_gen(num):
+    for cand in range(2, num+1):
+        for i in range (2, cand):
+            if (cand % i) == 0:
+                break
+        else:
+            yield cand
+
+def x2_gen(list2):
+    for num in list2:
+        yield num*num
+
+print(sum(x2_gen(prime_gen(5))))

Chapter04/iterators/iterator1.py

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+#iterator1.py
+#example 1: iterating on a list
+for x in [1,2,3]:
+    print(x)
+
+#example 2: iterating on a string
+for x in "Python for Geeks":
+    print(x, end="")
+print('')
+
+#example 3: iterating on a dictionary
+week_days = {1:'Mon', 2:'Tue',
+             3:'Wed', 4:'Thu',
+             5:'Fri', 6:'Sat', 7:'Sun'}
+for k in week_days:
+	print(k, week_days[k])
+
+#example 4: iterating on a file
+for row in open('abc.txt'):
+    print(row, end="")

Chapter04/iterators/iterator2.py

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+#iterator2.py
+class Week:
+    def __init__(self):
+        self.days = {1:'Monday', 2: "Tuesday",
+                     3:"Wednesday", 4: "Thursday",
+                     5:"Friday", 6:"Saturday", 7:"Sunday"}
+        self._index = 1
+
+    def __iter__(self):
+        self._index = 1
+        return self
+
+    def __next__(self):
+
+        if self._index < 1 | self._index > 8:
+            raise StopIteration
+        else:
+            ret_value =  self.days[self._index]
+            self._index +=1
+        return ret_value
+
+if(__name__ == "__main__"):
+    wk = Week()
+    for day in wk:
+        print(day)

Chapter04/iterators/iterator3.py

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+#iterator3.py
+class Week:
+    def __init__(self):
+        self.days = {1:'Monday', 2: "Tuesday",
+                     3:"Wednesday", 4: "Thursday",
+                     5:"Friday", 6:"Saturday", 7:"Sunday"}
+        self._index = 1
+
+    def __iter__(self):
+        self._index = 1
+        return self
+
+    def __next__(self):
+
+        if self._index < 1 | self._index > 8:
+            raise StopIteration
+        else:
+            ret_value =  self.days[self._index]
+            self._index +=1
+        return ret_value
+
+if(__name__ == "__main__"):
+    wk = Week()
+    iter1 = iter(wk)
+    iter2 = iter(wk)
+    print(iter1.__next__())
+    print(iter2.__next__())
+    print(next(iter1))
+    print(next(iter2))

Chapter04/iterators/iterator4.py

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+#iterator4.py
+class Week:
+    def __init__(self):
+        self.days = {1: 'Monday', 2: "Tuesday",
+                     3: "Wednesday", 4: "Thursday",
+                     5: "Friday", 6: "Saturday", 7: "Sunday"}
+
+    def __iter__(self):
+        return WeekIterator(self.days)
+
+class WeekIterator:
+    def __init__(self, dayss):
+        self.days_ref = dayss
+        self._index = 1
+
+    def __iter__(self):
+        return self;
+
+    def __next__(self):
+        if self._index < 1 | self._index > 8:
+            raise StopIteration
+        else:
+            ret_value =  self.days_ref[self._index]
+            self._index +=1
+        return ret_value
+
+if(__name__ == "__main__"):
+    wk = Week()
+    iter1 = iter(wk)
+    iter2 = iter(wk)
+    print(iter1.__next__())
+    print(iter2.__next__())
+    print(next(iter1))
+    print(next(iter2))