Learning Circle : python #3 - ex15 ~ ex21

youngjin.han/learning-node02-2020.org

@@ -1,3 +1,9 @@
+* 2020-05-22
+**** TODO Lecture content
+     - Same structure as "Python #2"
+     - Exercises 15-22
+**** Lecture material
+     - Available on https://cloud.ungleich.ch/s/435FyfrQyEq6oF3
 * 2020-05-20
 *** Python #2:
 **** DONE Lecture content

youngjin.han/python-the-hard-way/ex15.py

@@ -0,0 +1,19 @@
+from sys import argv # include argv
+
+script, filename = argv # define a argument
+
+txt = open(filename) # open the file
+
+print(f"Here's your file {filename}:") # print a script
+print(txt.read()) # read and print the text from the file
+
+txt.close()
+
+print("Type the filename again:") # print a script
+file_again = input("> ") # input from stdin
+
+txt_again = open(file_again) # open the file
+
+print(txt_again.read()) # read and print the text from the file
+
+txt_again.close()

youngjin.han/python-the-hard-way/ex15_sample.txt

@@ -0,0 +1,3 @@
+This is stuff I typed into a file.
+It is really cool stuff.
+Lots and lots of fun to have in here.

youngjin.han/python-the-hard-way/ex16.py

@@ -0,0 +1,41 @@
+from sys import argv
+
+script, filename = argv
+
+print(f"We're going to erase {filename}.")
+print("If you don't want that, hit CTRL-C (^C).")
+print("If you do want that, hit RETURN.")
+
+input("?")
+
+print("Opening the file...")
+target = open(filename, 'w')
+
+print("Truncating the file. Goodbye!")
+target.truncate()
+
+print("Now I'm going to ask you for three lines.")
+
+line1 = input("line 1: ")
+line2 = input("line 2: ")
+line3 = input("line 3: ")
+
+print("I'm going to write these to the file.")
+
+#target.write(line1)
+#target.write("\n")
+#target.write(line2)
+#target.write("\n")
+#target.write(line3)
+#target.write("\n")
+target.write(f"""{line1}
+{line2}
+{line3}
+"""
+)
+
+print("And finally, we close it.")
+target.close()
+
+txt = open(filename)
+print(txt.read())

youngjin.han/python-the-hard-way/ex16_file_write.txt

@@ -0,0 +1,3 @@
+1234
+5678
+90-=

youngjin.han/python-the-hard-way/ex16_file_write_multiple_line.txt

@@ -0,0 +1,3 @@
+line1
+line2
+line3

youngjin.han/python-the-hard-way/ex17.py

@@ -0,0 +1,28 @@
+from sys import argv
+from os.path import exists
+import shutil
+
+script, from_file, to_file = argv
+
+print(f"Copying from {from_file} to {to_file}")
+
+#open(to_file, 'w').write(open(from_file).read())
+shutil.copyfile(from_file, to_file)
+
+# we could do these two on one line, how?
+#in_file = open(from_file)
+#indata = in_file.read()
+
+#print(f"The input file is {len(indata)} bytes long")
+
+#print(f"Does the output file exist? {exists(to_file)}")
+#print("Ready, hit RETURN to continue, CTRL-C to abort.")
+#input()
+
+#out_file = open(to_file, 'w')
+#out_file.write(indata)
+
+print("Alright, all done.")
+
+#out_file.close()
+#in_file.close()

youngjin.han/python-the-hard-way/ex17_new2_test.txt

@@ -0,0 +1 @@
+This is a test file.

youngjin.han/python-the-hard-way/ex17_new3_test.txt

@@ -0,0 +1 @@
+This is a test file.

youngjin.han/python-the-hard-way/ex17_new_test.txt

@@ -0,0 +1 @@
+This is a test file.

youngjin.han/python-the-hard-way/ex17_test.txt

@@ -0,0 +1 @@
+This is a test file.

youngjin.han/python-the-hard-way/ex18.py

@@ -0,0 +1,23 @@
+# this one is like your scripts with argv
+def print_two(*args):
+    arg1, arg2 = args
+    print(f'arg1: {arg1}, arg2: {arg2}')
+
+# ok, that *args is actually pointless, we can just do this
+def print_two_again(arg1, arg2):
+    print(f"arg1: {arg1}, arg2: {arg2}")
+    
+# this just takes one argument
+def print_one(arg1):
+    print(f"arg1: {arg1}")
+
+# this one takes no arguments
+def print_none():
+    print("I got nothin'.")
+
+
+print_two("Zed","Shaw")
+print_two_again("Zed","Shaw")
+print_one("First!")
+
+print_none()

youngjin.han/python-the-hard-way/ex19.py

@@ -0,0 +1,63 @@
+def cheese_and_crackers(cheese_count, boxes_of_crackers): # define a function
+    print(f"You have {cheese_count} cheeses!") # print cheese_count
+    print(f"You have {boxes_of_crackers} boxes of crackers!") # print boxex_of_crackers
+    print("Man that's enough for a party!") # print a script
+    print("Get a blanket.\n") # print a script
+
+def my_f(arg1, arg2):
+    total = arg1 + arg2
+    print(f"arg1: {arg1}, arg2: {arg2}, total: {total}")
+
+print("We can just give the function numbers directly:") # print a script
+cheese_and_crackers(20, 30) # call the function
+
+
+print("OR, we can use variables from our script:") # print a script
+amount_of_cheese = 10 # define a value
+amount_of_crackers = 50 # define a value
+
+cheese_and_crackers(amount_of_cheese, amount_of_crackers) # call the function
+
+
+print("We can even do math inside too:") # print a script
+cheese_and_crackers(10 + 20, 5 + 6) # call the function
+
+
+print("And we can combine the two, variables and math:") # print a script
+cheese_and_crackers(amount_of_cheese + 100, amount_of_crackers + 1000) # call the function
+
+my_f(1, 2)
+my_f(2*4, 8/2)
+my_f("2*4", "8/2")
+my_f("not", "bad")
+
+n_arg1 = 1
+n_arg2 = 2
+
+my_f(n_arg1, n_arg2)
+
+s_arg1 = "good"
+s_arg2 = "luck"
+
+my_f(s_arg1, s_arg2)
+
+t_arg1 = 8/2+3
+t_arg2 = 8%2
+
+my_f(t_arg1, t_arg2)
+
+
+m_a1 = """line1
+line2
+line3
+"""
+m_a2 = """line4
+line5
+line6
+"""
+my_f(m_a1, m_a2)
+
+my_f(open("test.txt").read(), open("test.txt").read())
+
+f = "{} {}"
+my_f(f.format(1, 2), f.format(3, 4))

youngjin.han/python-the-hard-way/ex20.py

@@ -0,0 +1,35 @@
+from sys import argv # import argv
+
+script, input_file = argv # define argv
+
+def print_all(f): # define a function
+    print(f.read()) # print all
+
+def rewind(f): # define a function
+    f.seek(0) # jump the starting point of a file
+
+def print_a_line(line_count, f): # define a function
+    print(line_count, f.readline()) # pinrt a line on the file
+
+current_file = open(input_file) # open a file
+
+print("First let's print the whole file:\n") # print a script
+
+print_all(current_file) # call the function
+
+print("Now let's rewind, kind of like a tape.") # print a script
+
+rewind(current_file) # call the function
+
+print("Let's print three lines:") # print a script
+
+current_line = 1 # define a value
+print_a_line(current_line, current_file) # call the function
+
+#current_line = current_line + 1 # define a value
+current_line += 1
+print_a_line(current_line, current_file) # call the function
+
+#current_line = current_line + 1 # define a value
+current_line += 1
+print_a_line(current_line, current_file) # call the function

youngjin.han/python-the-hard-way/ex20_test.txt

@@ -0,0 +1,3 @@
+This is line 1
+This is line 2
+This is line 3

youngjin.han/python-the-hard-way/ex21.py

@@ -0,0 +1,33 @@
+def add(a, b):
+    print(f"ADDING {a} + {b}")
+    return a + b
+
+def subtract(a, b):
+    print(f"SUBTRACTING {a} - {b}")
+    return a - b
+
+def multiply(a, b):
+    print(f"MULTIPLYING {a} * {b}")
+    return a * b - b
+
+def divide(a, b):
+    print(f"DIVIDING {a} / {b}")
+    return a / b
+
+
+print("Let's do some math with just functions!")
+
+age = add(30, 5)
+height = subtract(78, 4)
+weight = multiply(90, 2)
+iq = divide(100, 2)
+
+print(f"Age: {age}, Height: {height}, Weight: {weight}, IQ: {iq}")
+
+
+# A puzzle for the extra credit, type it in anyway.
+print("Here is a puzzle.")
+
+what = add(age, subtract(height, multiply(weight, divide(iq, 2))))
+
+print("That becomes: ", what, "Can you do it by hand?")

youngjin.han/python-the-hard-way/ex22.py

@@ -0,0 +1,22 @@
+import sys
+script, input_encoding, error = sys.argv
+
+def main(language_file, encoding, errors):
+line = language_file.readline()
+
+if line:
+print_line(line, encoding, errors)
+return main(language_file, encoding, errors)
+
+
+def print_line(line, encoding, errors):
+next_lang = line.strip()
+raw_bytes = next_lang.encode(encoding, errors=errors)
+cooked_string = raw_bytes.decode(encoding, errors=errors)
+
+print(raw_bytes, "<===>", cooked_string)
+
+
+languages = open("languages.txt", encoding="utf-8")
+
+main(languages, input_encoding, error)

youngjin.han/python-the-hard-way/test.txt

@@ -0,0 +1,3 @@
+Mary had a little lamb
+Its fleece was white as snow
+It was also tasty

youngjin.han/python.org

@@ -1,3 +1,32 @@
+* 2020-05-22
+** note
+   - ex15.py
+     - The argument method is better than using stdin. becouse bash-completion could be used.
+     - python3.8 shell
+       - >>> filename=input()
+       - ex15_sample.txt
+       - >>> txt = open(filename)
+       - >>> txt_script = txt.read()
+       - >>> print(txt_script)
+       - This is stuff I typed into a file.
+       - It is really cool stuff.
+       - Lots and lots of fun to have in here
+   - ex16.py
+     - 'w' is to open a file on write mode.
+     - If a file is openned with 'w', target.truncate() should not be need. the 'w' mode always overwrite a file.
+   - ex17.py
+     - cat is concatenate files to stdout
+     - If file.close() is not called, the file which is openned by python chould not be modified on orther programs.
+   - ex18.py
+     - none
+   - ex19.py
+     - none
+   - ex20.py
+     - file.seek is to move to new file posotion
+   - ex21.py
+     -
+   - ex22.py
+     -
 * 2020-05-20
 ** note
    - ex8.py
@@ -15,7 +44,6 @@
      - none
    - ex14.py
      - none
-
 * 2020-05-18
 ** note
    - ex1.py