Merge branch 'gh-pages' into patch-6

README.md

@@ -9,4 +9,4 @@ for instructions on formatting, building, and submitting material,
 or run `make` in this directory for a list of helpful commands.
 
 Maintainer(s):
-Richard Vankoningsveld, @richyvk
+[Richard Vankoningsveld](https://github.com/richyvk) and [Carlos Martinez](https://github.com/c-martinez).

_episodes/02-variables.md

@@ -142,6 +142,7 @@ h
 *   The difference between stop and start is the slice's length.
 *   Taking a slice does not change the contents of the original string. Instead,
     the slice is a copy of part of the original string.
+
 ~~~
 atom_name = 'sodium'
 print(atom_name[0:3])

_episodes/03-types-conversion.md

@@ -22,17 +22,17 @@ keypoints:
 ## Every value has a type.
 
 *   Every value in a program has a specific type.
-*   Integer (`int`): counting numbers like 3 or -512.
+*   Integer (`int`): whole numbers like 3 or -512.
 *   Floating point number (`float`): fractional numbers like 3.14159 or -2.5.
-    *   Integers are used to count, floats are used to measure.
+*   Whole numbers may also be stored as floats, e.g. `1.0`, but `1.0` would still be stored as a `float`.
 *   Character string (usually called "string", `str`): text.
     *   Written in either single quotes or double quotes (as long as they match).
-    *   The quotation marks aren't printed when the string is displayed.
+    *   The quotation marks aren't printed using `print()`, but may appear when viewing a value in the Jupyter Notebook or other Python interpreter.
 
 ## Use the built-in function `type` to find the type of a value.
 
 *   Use the built-in function `type` to find out what type a value has.
-*   Works on variables as well.
+*   This works on variables as well.
     *   But remember: the *value* has the type --- the *variable* is just a label.
     *   When you change the value of a variable to a new data type, the results of `print(type(your_variable))` will change accordingly.
 
@@ -82,7 +82,7 @@ TypeError: unsupported operand type(s) for -: 'str' and 'str'
 ~~~
 {: .error}
 
-## You can use the "+" and "*" operators on strings.
+## You can use the `+` and `*` operators on strings.
 
 *   "Adding" character strings concatenates them.
 
@@ -98,6 +98,7 @@ Ahmed Walsh
 
 *   Multiplying a character string by an integer _N_ creates a new string that consists of that character string repeated  _N_ times.
     *   Since multiplication is repeated addition.
+* There are more ways that traditional math operators will work on other data types.  There isn't a perfect formula for figuing out what they do, so experimentation is valuable.
 
 ~~~
 separator = '=' * 10
@@ -262,12 +263,26 @@ first is 2 and second is 5
 > 5. Number of reference queries in a year.
 > 6. Average library classes taught per semester.
 >
+> > ## Solution
+> > 1. Integer  
+> > 2. Float  
+> > 3. String
+> > 4. Integer  
+> > 5. Integer  
+> > 6. Float  
+> {: .solution}
 {: .challenge}
 
 > ## Division Types
+> There are three different types of division:
+> 1. 'Normal' division (aka floating-point division) is what most people may be
+> familiar with: 5 / 2 = 2.5
+> 2. Floor division, which cuts out the part after the period: 5 / 2 = 2
+> 3. Modulo division, which only keeps the remained after division: 5 / 2 = 1
 >
-> In Python 3, the `//` operator performs integer (whole-number) floor division, the `/` operator performs floating-point
-> division, and the '%' (or *modulo*) operator calculates and returns the remainder from integer division:
+> In Python 3,  the `/` operator performs floating-point division, the `//`
+> operator performs floor division, and the '%' (or *modulo*) operator
+> calculates the modulo division:
 >
 > ~~~
 > print('5 // 3:', 5//3)
@@ -283,28 +298,30 @@ first is 2 and second is 5
 > ~~~
 > {: .output}
 >
-> If `num_students` is the number of students enrolled in a course,
-> and `num_per_class` is the number that can attend a single class,
+> If `num_students` is the number of students enrolled in a course (let say 600),
+> and `num_per_class` is the number that can attend a single class (let say 42),
 > write an expression that calculates the number of classes needed
 > to teach everyone.
 >
 > > ## Solution
 > > Depending on requirements it might be important to detect when the number of students per class doesn't divide the
 > > number of students evenly. Detect it with the `%` operator and test if the remainder that it returns is greater than
 > > 0.
-> > 
+> >
 > >
 > > ~~~
 > > num_students = 600
 > > num_per_class = 42
 > > num_classes = num_students // num_per_class
 > > remainder = num_students % num_per_class
 > >
-> > print(num_students, 'students,', num_per_class, 'per class:', num_classes)
+> > print(num_students, 'students,', num_per_class, 'per class')
+> > print(num_classes, ' full classes, plus an extra class with only ', remainder, 'students')
 > > ~~~
 > > {: .python}
 > > ~~~
-> > 600 students, 42 per class: 14
+> > 600 students, 42 per class
+> > 14  full classes, plus an extra class with only  12 students
 > > ~~~
 > > {: .output}
 > {: .solution}
@@ -327,6 +344,8 @@ first is 2 and second is 5
 > ~~~
 > {: .output}
 >
+> **Note:** conversion is some times also called typecast.
+>
 > If the conversion doesn't make sense, however, an error message will occur
 >
 > ~~~
@@ -354,30 +373,29 @@ first is 2 and second is 5
 > print("fractional string to int:", int("3.4"))
 > ~~~
 > {: .python}
-> 
+>
 > > ## Solution
-> > What do you expect this program to do? It would not be so unreasonable to expect the Python 3 `int` command to
-> > convert the string "3.4" to 3.4 and an additional type conversion to 3. After all, Python 3 performs a lot of other
+> > What do you expect this program to do? It would not be so unreasonable to
+> > expect the Python `int` command to convert the string "3.4" to 3.4 and an
+> > additional type conversion to 3. After all, Python performs a lot of other
 > > magic - isn't that part of its charm?
-> > 
-> > However, Python 3 throws an error. Why? To be consistent, possibly. If you ask Python to perform two consecutive
-> > typecasts, you must convert it explicitly in code.
+> >
+> > However, Python throws an error. Why? To be consistent, possibly. If you
+> > ask Python to perform two consecutive typecasts, you must convert it
+> > explicitly in code.
 > >
 > > ~~~
-> > int("3.4")
-> > int(float("3.4"))
+> > num_as_string = "3.4"
+> > num_as_float = float(num_as_string)
+> > num_as_int = int(num_as_float)
+> > print(num_as_int)
 > > ~~~
 > > {: .python}
 > > ~~~
-> > In [2]: int("3.4")
-> > ---------------------------------------------------------------------------
-> > ValueError                                Traceback (most recent call last)
-> > <ipython-input-2-ec6729dfccdc> in <module>()
-> > ----> 1 int("3.4")
-> > ValueError: invalid literal for int() with base 10: '3.4'
 > > 3
 > > ~~~
 > > {: .output}
+> > We could also write it in a single line like this: `int(float("3.4"))`
 > {: .solution}
 {: .challenge}
 
@@ -402,6 +420,13 @@ first is 2 and second is 5
 >
 > > ## Solution
 > >
-> > Answer: 1 and 4
+> > Answer: 1 and 4.
+> >
+> > 1. is correct
+> > 2. gives 2.1
+> > 3. gives an arror because we cannot convert text to int directly
+> > 4. is correct
+> > 5. gives 2 (as an integer not as a float)
+> > 6. gives an error because `second` is a string.
 > {: .solution}
 {: .challenge}

_episodes/04-built-in.md

@@ -37,12 +37,14 @@ adjustment = 0.5   # Neither is this - anything after '#' is ignored.
 
 *   We have seen some functions already --- now let's take a closer look.
 *   An *argument* is a value passed into a function.
+*   Any arguments you want to pass into a function must go into the `()`
+    * print("I'm an argument and must go here.")
+*   You must always use parentheses, because this is how Python knows you are calling a function.
+    * You leave them empty if you don't want or need to pass any arguments in.
 *   `len` takes exactly one.
 *   `int`, `str`, and `float` create a new value from an existing one.
 *   `print` takes zero or more.
-*   `print` with no arguments prints a blank line.
-    *   Must always use parentheses, even if they're empty,
-        so that Python knows a function is being called.
+    *   `print()` prints a blank line.
 
 ~~~
 print('before')

_episodes/06-libraries.md

@@ -166,7 +166,7 @@ cos(pi) is -1.0
 > >
 > > The [datetime module](https://docs.python.org/3/library/datetime.html) seems like it could help you.
 > >
-> > 
+> >
 > > You could use `date(year, month, date).isoformat()` to convert your date:
 > >
 > > ~~~
@@ -186,14 +186,15 @@ cos(pi) is -1.0
 > > ~~~
 > > {: .python}
 > >
+> {: .solution}
 {: .challenge}
 
 
 > ## Jigsaw Puzzle (Parson's Problem) Programming Example
-> 
+>
 > Rearrange the following statements so that a random
-> DNA base is printed.  Not all statements may be needed.  Feel free to use/add 
-> intermediate variables. 
+> DNA base is printed.  Not all statements may be needed.  Feel free to use/add
+> intermediate variables.
 >
 > ~~~
 > bases="ACTTGCTTGAC"
@@ -248,7 +249,7 @@ cos(pi) is -1.0
 > > ~~~
 > > {: .python}
 > >
-> > can bewritten as
+> > can be written as
 > >
 > > ~~~
 > > import math
@@ -268,13 +269,13 @@ cos(pi) is -1.0
 > ## There Are Many Ways To Import Libraries!
 >
 > Match the following print statements with the appropriate library calls
-> 
+>
 > Library calls:
 > 1. `from math import sin,pi`
 > 2. `import math`
 > 3. `import math as m`
 > 4. `from math import *`
-> 
+>
 > Print commands:
 > 7. `print("sin(pi/2) =",sin(pi/2))`
 > 8. `print("sin(pi/2) =",m.sin(m.pi/2))`

_episodes/11-lists.md

@@ -134,7 +134,7 @@ primes after removing last item: [2, 3, 5, 7]
 *   Use `[]` on its own to represent a list that doesn't contain any values.
     *   "The zero of lists."
 *   Helpful as a starting point for collecting values
-    (which we will see in the [next episode]({{page.root}}/09-for-loops/)).
+    (which we will see in the [next episode]({{page.root}}/12-for-loops/)).
 
 ## Lists may contain values of different types.
 
@@ -183,7 +183,7 @@ TypeError: 'str' object does not support item assignment
 ## Indexing beyond the end of the collection is an error.
 
 *   Python reports an `IndexError` if we attempt to access a value that doesn't exist.
-    *   This is a kind of [runtime error]({{ page.root }}/05-error-messages/).
+    *   This is a kind of runtime error.
     *   Cannot be detected as the code is parsed
         because the index might be calculated based on data.
 

_episodes/12-for-loops.md

@@ -98,12 +98,15 @@ for number in [2, 3, 5]:
 *   The loop variable, `number`, is what changes for each *iteration* of the loop.
     *   The "current thing".
 
-## Loop variables can be called anything.
-
-*   As with all variables, loop variables are:
-    *   Created on demand.
-    *   Meaningless: their names can be anything at all.
-
+## Loop variable names follow the normal variable name conventions.
+
+*   Loop variables will:
+    *   Be created on demand during the course of each loop.
+    *   Persist after the loop finishes.
+        * Use a new variable name to avoid overwriting a data collection you need to keep for later
+    *   Often be used in the course of the loop
+        * So give them a meaningful name you'll understand as the body code in your loop grows.
+        * Example: `for single_letter in ['A', 'B', 'C', 'D']:` instead of `for asdf in ['A', 'B', 'C', 'D']:`
 ~~~
 for kitten in [2, 3, 5]:
     print(kitten)
@@ -152,6 +155,26 @@ a range is not a list: range(0, 3)
 ~~~
 {: .output}
 
+## Or use `range` to repeat an action an arbitrary number of times.
+
+*   You don't actually have to use the iterable variable's value.
+*   Use this structure to simply repeat an action some number of times.
+    *   That number of times goes into the `range` function.
+
+~~~
+for number in range(5):
+    print("Again!")
+~~~
+{: .python}
+~~~
+Again!
+Again!
+Again!
+Again!
+Again!
+~~~
+{: .output}
+
 ## The Accumulator pattern turns many values into one.
 
 *   A common pattern in programs is to:

setup.md

@@ -6,14 +6,14 @@ permalink: /setup/
 
 ## Installing Python Using Anaconda
 
-[Python][python] is great for general-purpose programming, and a popular language 
+[Python][python] is great for general-purpose programming and is a popular language 
 for scientific computing as well. Installing all of the packages required for this 
-lesosn individually can be a bit difficult, however, so we recommend the all-in-one
+lessons individually can be a bit difficult, however, so we recommend the all-in-one
 installer [Anaconda][anaconda].
 
 Regardless of how you choose to install it, please make sure you install Python
-version 3.x (e.g., Python 3.6 version). Also, please set up your python environment at 
-least a day in advance of the workshop.  If you encounter problems with the 
+version 3.x (e.g., Python 3.6 version). Also, please set up your Python environment at 
+least a day in advance of the workshop. If you encounter problems with the 
 installation procedure, ask your workshop organizers via e-mail for assistance so
 you are ready to go as soon as the workshop begins.
 
@@ -28,12 +28,12 @@ you are ready to go as soon as the workshop begins.
    default settings. The only exception is to check the 
    **Make Anaconda the default Python** option.
 
-### Mac OS X - [Video tutorial][video-mac]
+### macOS - [Video tutorial][video-mac]
 
 1. Open [http://continuum.io/downloads][continuum-mac]
    with your web browser.
 
-2. Download the Python 3 installer for OS X.
+2. Download the Python 3 installer for macOS.
 
 3. Install Python 3 using all of the defaults for installation.
 
@@ -77,7 +77,7 @@ for Python. If you installed Python using Anaconda, Spyder should already be on
 you did not use Anaconda, use the Python package manager pip
 (see the [Spyder website][spyder-install] for details.)
 
-To start Spyder, open a terminal or git bash and type the command:
+To start Spyder, open a terminal or Git Bash and type the command:
 
 ~~~
 $ spyder3
@@ -93,9 +93,9 @@ $ python
 {: .bash}
 
 [anaconda]: https://www.continuum.io/anaconda
-[continuum-mac]: http://continuum.io/downloads#_macosx
-[continuum-linux]: http://continuum.io/downloads#_unix
-[continuum-windows]: http://continuum.io/downloads#_windows
+[continuum-mac]: http://continuum.io/downloads#macos
+[continuum-linux]: http://continuum.io/downloads#linux
+[continuum-windows]: http://continuum.io/downloads#windows
 [python]: https://python.org
 [spyder]: https://pythonhosted.org/spyder/
 [spyder-install]: https://pythonhosted.org/spyder/installation.html