Merge pull request #926

Swapping the order of episodes on lists and loops

Author: maxim-belkin

README.md

@@ -31,8 +31,8 @@ This lesson is also available in [R][R] and [MATLAB][MATLAB].
 | 1 | [Python Fundamentals][episode01] | 30 | What basic data types can I work with in Python?<br>How can I create a new variable in Python?<br>Can I change the value associated with a variable after I create it? |
 | 2 | [Analyzing Patient Data][episode02] | 60 | How can I process tabular data files in Python? |
 | 3 | [Visualizing Tabular Data][episode03] | 50 | How can I visualize tabular data in Python?<br>How can I group several plots together? |
-| 4 | [Repeating Actions with Loops][episode04] | 30 | How can I do the same operations on many different values? |
-| 5 | [Storing Multiple Values in Lists][episode05] | 30 | How can I store many values together? |
+| 4 | [Storing Multiple Values in Lists][episode04] | 30 | How can I store many values together? |
+| 5 | [Repeating Actions with Loops][episode05] | 30 | How can I do the same operations on many different values? |
 | 6 | [Analyzing Data from Multiple Files][episode06] | 20 | How can I do the same operations on many different files? |
 | 7 | [Making Choices][episode07] | 30 | How can my programs do different things based on data values? |
 | 8 | [Creating Functions][episode08] | 30 | How can I define new functions?<br>What’s the difference between defining and calling a function?<br>What happens when I call a function? |
@@ -107,8 +107,8 @@ industry and government. More information can be found [here][cp-about].
 [episode01]: https://swcarpentry.github.io/python-novice-inflammation/01-intro/index.html
 [episode02]: https://swcarpentry.github.io/python-novice-inflammation/02-numpy/index.html
 [episode03]: https://swcarpentry.github.io/python-novice-inflammation/03-matplotlib/index.html
-[episode04]: https://swcarpentry.github.io/python-novice-inflammation/04-loop/index.html
-[episode05]: https://swcarpentry.github.io/python-novice-inflammation/05-lists/index.html
+[episode04]: https://swcarpentry.github.io/python-novice-inflammation/04-lists/index.html
+[episode05]: https://swcarpentry.github.io/python-novice-inflammation/05-loop/index.html
 [episode06]: https://swcarpentry.github.io/python-novice-inflammation/06-files/index.html
 [episode07]: https://swcarpentry.github.io/python-novice-inflammation/07-cond/index.html
 [episode08]: https://swcarpentry.github.io/python-novice-inflammation/08-func/index.html

_episodes/05-lists.md renamed to _episodes/04-lists.md

@@ -20,9 +20,17 @@ list[2:9]), in the same way as strings and arrays."
 - "Strings are immutable (i.e., the characters in them cannot be changed)."
 ---
 
-Similar to a string that can contain many characters, a list is a container that can store many
-values. Unlike NumPy arrays, lists are built into the language (so we don't have to load a library
-to use them).
+In the previous episode, we analyzed a single file with inflammation data. Our goal, however, is to
+process all the inflammation data we have, which means that we still have eleven more files to go!
+
+The natural first step is to collect the names of all the files that we have to process. In Python,
+a list is a way to store multiple values together. In this episode, we will learn how to store
+multiple values in a list as well as how to work with lists.
+
+## Python lists
+
+Unlike NumPy arrays, lists are built into the language so we do not have to load a library
+to use them.
 We create a list by putting values inside square brackets and separating the values with commas:
 
 ~~~
@@ -57,22 +65,6 @@ Yes, we can use negative numbers as indices in Python. When we do so, the index
 last element in the list, `-2` the second to last, and so on.
 Because of this, `odds[3]` and `odds[-1]` point to the same element here.
 
-If we loop over a list, the loop variable is assigned to its elements one at a time:
-
-~~~
-for number in odds:
-    print(number)
-~~~
-{: .language-python}
-
-~~~
-1
-3
-5
-7
-~~~
-{: .output}
-
 There is one important difference between lists and strings:
 we can change the values in a list,
 but we cannot change individual characters in a string.
@@ -308,33 +300,6 @@ odds: [1, 3, 5, 7]
 ~~~
 {: .output}
 
-> ## Turn a String Into a List
->
-> Use a for-loop to convert the string "hello" into a list of letters:
->
-> ~~~
-> ['h', 'e', 'l', 'l', 'o']
-> ~~~
-> {: .language-python}
->
-> Hint: You can create an empty list like this:
->
-> ~~~
-> my_list = []
-> ~~~
-> {: .language-python}
->
-> > ## Solution
-> > ~~~
-> > my_list = []
-> > for char in 'hello':
-> >     my_list.append(char)
-> > print(my_list)
-> > ~~~
-> > {: .language-python}
-> {: .solution}
-{: .challenge}
-
 Subsets of lists and strings can be accessed by specifying ranges of values in brackets,
 similar to how we accessed ranges of positions in a NumPy array.
 This is commonly referred to as "slicing" the list/string.