Adding chapter 4 source code

chapter4/errors/abc.txt

@@ -0,0 +1 @@
+Hello WorldEnd

chapter4/errors/exception1.py

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+#exception1.py
+try:
+    #print (x)
+    x = 5
+    y = 1
+    z = x /y
+    print('x'+y)
+
+except NameError as e:
+    print(e)
+except ZeroDivisionError:
+    print("Division by 0 is not allowed")
+except Exception as e:
+    print("An error occured")
+    print(e)

chapter4/errors/exception2.py

@@ -0,0 +1,10 @@
+#exception2.py
+try:
+    f = open("abc.txt", "w")
+except Exception as e:
+    print("Error:" + e)
+else:
+    f.write("Hello World")
+    f.write("End")
+finally:
+    f.close()

chapter4/errors/exception3.py

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+#exception3.py
+import math
+def sqrt(num):
+
+    if not isinstance(num, (int, float)) :
+        raise TypeError("only numbers are allowed")
+    if num < 0:
+        raise Exception ("Negative number not supported")
+
+    return math.sqrt(num)
+
+if __name__ == "__main__":
+    try:
+        print(sqrt(9))
+        print(sqrt('a'))
+        print (sqrt(-9))
+    except Exception as e:
+        print(e)

chapter4/errors/exception4.py

@@ -0,0 +1,28 @@
+#exception3.py
+import math
+
+class NumTypeError(TypeError):
+    pass
+
+class NegativeNumError(Exception):
+    def __init__(self):
+        super().__init__("Negative number not supported")
+
+def sqrt(num):
+
+    if not isinstance(num, (int, float)) :
+        raise NumTypeError("only numbers are allowed")
+    if num < 0:
+        raise NegativeNumError
+
+    return math.sqrt(num)
+
+if __name__ == "__main__":
+    try:
+        print(sqrt(9))
+        print(sqrt('a'))
+        print (sqrt(-9))
+    except NumTypeError as e:
+        print(e)
+    except NegativeNumError as e:
+        print(e)

chapter4/files/1.txt

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+This is a sample file 1
+This is a test data 1

chapter4/files/2.txt

@@ -0,0 +1,2 @@
+This is a sample file 2
+This is a test data 2

chapter4/files/contextmgr1.py

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+#contextmgr1.py
+with open("myfile.txt",'w') as f1:
+    f1.write("This is a sample file\n")
+    lines = ["This is a test data\n", "in two lines\n"]
+    f1.writelines(lines)
+
+with open("myfile.txt",'r') as f2:
+    for line in f2.readlines():
+        print(line)

chapter4/files/multifilesread1.py

@@ -0,0 +1,6 @@
+#multifilesread1.py
+import fileinput
+with fileinput.input(files = ("1.txt",'2.txt') )as f:
+    for line in f:
+        print(f.filename())
+        print(line)

chapter4/files/myfile.txt

@@ -0,0 +1,3 @@
+This is a sample file
+This is a test data
+in two lines

chapter4/files/writereadfile.py

@@ -0,0 +1,16 @@
+#writereadfile.pywrite to a file and then read from it
+f1 = open("myfile.txt",'w')
+f1.write("This is a sample file\n")
+lines =["This is a test data\n", "in two lines\n"]
+f1.writelines(lines)
+f1.close()
+
+f2 = open("myfile.txt",'r')
+print(f2.read(4))
+print(f2.readline())
+print(f2.readline())
+
+f2.seek(0)
+for line in f2.readlines():
+    print(line)
+f2.close()

chapter4/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.

chapter4/iterators/generator1.py

@@ -0,0 +1,12 @@
+#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__())

chapter4/iterators/generator2.py

@@ -0,0 +1,19 @@
+#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))

chapter4/iterators/generator3.py

@@ -0,0 +1,7 @@
+#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__())

chapter4/iterators/generator4.py

@@ -0,0 +1,14 @@
+#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))))

chapter4/iterators/iterator1.py

@@ -0,0 +1,20 @@
+#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="")

chapter4/iterators/iterator2.py

@@ -0,0 +1,25 @@
+#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)

chapter4/iterators/iterator3.py

@@ -0,0 +1,29 @@
+#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))

chapter4/iterators/iterator4.py

@@ -0,0 +1,34 @@
+#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))

chapter4/logging/logging1.py

@@ -0,0 +1,6 @@
+#logging1.py
+import logging
+#logging.basicConfig(level=logging.DEBUG)
+logging.debug("This is a debug message")
+logging.warning("This is a warning message")
+logging.info("This is an info message")

chapter4/logging/logging2.py

@@ -0,0 +1,9 @@
+#logging2.py
+import logging
+logger1 = logging.getLogger("my_logger")
+logging.basicConfig()
+logger1.setLevel(logging.INFO)
+logger1.warning("This is a warning message")
+logger1.info("This is a info message")
+logger1.debug("This is a debug messag")
+logging.info("This is an info message")

chapter4/logging/logging3.py

@@ -0,0 +1,12 @@
+#logging3.py
+import logging
+logger = logging.getLogger('my_logger')
+my_handler = logging.StreamHandler()
+my_formatter = logging.Formatter('%(asctime)s - '
+                  '%(name)s - %(levelname)s - %(message)s')
+my_handler.setFormatter(my_formatter)
+logger.addHandler(my_handler)
+logger.setLevel(logging.INFO)
+logger.warning("This is a warning message")
+logger.info("This is an info message")
+logger.debug("This is a debug message")

chapter4/logging/logging3A.py

@@ -0,0 +1,11 @@
+#logging3A.py
+import logging
+logger = logging.getLogger('my_logger')
+logging.basicConfig(handlers=[logging.StreamHandler()],
+                    format="%(asctime)s - %(name)s - "
+                           "%(levelname)s - %(message)s",
+                    level=logging.INFO)
+
+logger.warning("This is a warning message")
+logger.info("This is an info message")
+logger.debug("This is a debug message")

chapter4/logging/logging4.py

@@ -0,0 +1,10 @@
+#logging4.py
+import logging
+
+logging.basicConfig(filename='logs/logging4.log'
+                    ,level=logging.DEBUG)
+logger = logging.getLogger('my_logger')
+logger.setLevel(logging.INFO)
+logger.warning("This is a warning message")
+logger.info("This is a info message")
+logger.debug("This is a debug message")

chapter4/logging/logging5.py

@@ -0,0 +1,27 @@
+#logging5.py
+import logging
+logger = logging.getLogger('my_logger')
+logger.setLevel(logging.DEBUG)
+console_handler = logging.StreamHandler()
+file_handler = logging.FileHandler("logs/logging5.log")
+#setting logging levels at the handler level
+console_handler.setLevel(logging.DEBUG)
+file_handler.setLevel(logging.INFO)
+
+#creating separate formatter for two handlers
+console_formatter = logging.Formatter(
+                  '%(name)s - %(levelname)s - %(message)s')
+file_formatter = logging.Formatter('%(asctime)s - '
+                  '%(name)s - %(levelname)s - %(message)s')
+
+#adding formatters to the handler
+console_handler.setFormatter(console_formatter)
+file_handler.setFormatter(file_formatter)
+#adding handlers to the logger
+logger.addHandler(console_handler)
+logger.addHandler(file_handler)
+
+logger.error("This is an error message")
+logger.warning("This is a warning message")
+logger.info("This is a info message")
+logger.debug("This is a debug message")

chapter4/logging/logging6.conf.yaml

@@ -0,0 +1,26 @@
+version: 1
+formatters:
+  console_formatter:
+    format: '%(name)s - %(levelname)s - %(message)s'
+  file_formatter:
+      format: '%(asctime)s - %(name)s - %(levelname)s - %(message)s'
+handlers:
+  console_handler:
+    class: logging.StreamHandler
+    level: DEBUG
+    formatter: console_formatter
+    stream: ext://sys.stdout
+
+  file_handler:
+    class: logging.FileHandler
+    level: INFO
+    formatter: file_formatter
+    filename: logs/logging6.log
+loggers:
+  my_logger:
+    level: DEBUG
+    handlers: [console_handler, file_handler]
+    propagate: no
+root:
+  level: ERROR
+  handlers: [console_handler]

chapter4/logging/logging6.py

@@ -0,0 +1,15 @@
+#logging6.py
+import logging
+import logging.config
+import yaml
+
+with open('logging6.conf.yaml', 'r') as f:
+    config = yaml.safe_load(f.read())
+    logging.config.dictConfig(config)
+
+logger = logging.getLogger('my_logger')
+
+logger.error("This is an error message")
+logger.warning("This is a warning message")
+logger.info("This is a info message")
+logger.debug("This is a debug message")

chapter4/logging/logs/logging3.log

@@ -0,0 +1,2 @@
+2021-02-02 16:56:14,794 - my_logger - WARNING - This is a warning message
+2021-02-02 16:56:14,794 - my_logger - INFO - This is a info message

chapter4/logging/logs/logging4.log

@@ -0,0 +1,6 @@
+WARNING:my_logger:This is a warning message
+INFO:my_logger:This is a info message
+WARNING:my_logger:This is a warning message
+INFO:my_logger:This is a info message
+WARNING:my_logger:This is a warning message
+INFO:my_logger:This is a info message

chapter4/logging/logs/logging5.log

@@ -0,0 +1,3 @@
+2021-02-02 17:57:27,716 - my_logger - ERROR - This is an error message
+2021-02-02 17:57:27,716 - my_logger - WARNING - This is a warning message
+2021-02-02 17:57:27,716 - my_logger - INFO - This is a info message

chapter4/logging/logs/logging6.log

@@ -0,0 +1,4 @@
+
+2021-02-02 18:35:45,372 - my_logger - ERROR - This is an error message
+2021-02-02 18:35:45,373 - my_logger - WARNING - This is a warning message
+2021-02-02 18:35:45,373 - my_logger - INFO - This is a info message