adds csv

learning_python3.md

@@ -1825,7 +1825,54 @@ We already saw a dictionaries which are good mapping structures but how can we s
 A hacky way would be to write a python file containing the `dict` and `import` it when we need it.
 But there are better ways.
 
-**TODO CSV**
+The table below probably makes you think of *excel*.
+We can use excel to create a text based **database** where the first line, called the **header**, defines what information is stored in the database.
+Every **row** after the header is an **entry** with the item's values.
+Sounds more complicated than it is.
+
+| description                   | urgency | done |
+|-------------------------------|---------|------|
+| go to the shops               | 9       | 0    |
+| install music computer        | 4       | 0    |
+| download python documentation | 7       | 1    |
+| bottle new beer               | 9       | 1    |
+
+
+We can *convert* this table to a **Comma Separated Value** file, which can easily be read by python.
+
+```csv
+description,urgency,done
+go to the shops,9,0
+install music computer,4,0
+download python documentation,7,1
+bottle new beer,9,1
+```
+
+If we save this to a blank file we can us the built-in `open` function to read and interpret the data as a `list` of `dict`.
+The code below does exactly that, first without list comprehension, secondly with.
+
+```python
+import csv
+
+with open("./data.csv", "r") as fp:
+    tasks = csv.DictReader(fp)
+    print(tasks)
+    for task in tasks:
+        print(task)
+
+
+with open("./data.csv", "r") as fp:
+    tasks = [task for task in csv.DictReader(fp)]
+
+print(tasks)
+```
+
+🏃 Try it
+---
+
+Adapt your task manager to read tasks for a CSV file.
+Implement the urgency to sort your tasks by importance.
+Don't delete tasks from the file but rather mark them as *done*.
 
 # Now for some useful scripting