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-rw-r--r--python.html.markdown20
1 files changed, 15 insertions, 5 deletions
diff --git a/python.html.markdown b/python.html.markdown
index 541bd36d..2b43c5fc 100644
--- a/python.html.markdown
+++ b/python.html.markdown
@@ -63,7 +63,7 @@ allow you to write Python 3 code that will run on Python 2, so check out the Pyt
# to carry out normal division with just one '/'.
from __future__ import division
11/4 # => 2.75 ...normal division
-11//4 # => 2 ...floored division
+11//4 # => 2 ...floored division
# Modulo operation
7 % 3 # => 1
@@ -132,6 +132,7 @@ z = "The items in the basket are %s and %s" % (x,y)
# A newer way to format strings is the format method.
# This method is the preferred way
+"{} is a {}".format("This", "placeholder")
"{0} can be {1}".format("strings", "formatted")
# You can use keywords if you don't want to count.
"{name} wants to eat {food}".format(name="Bob", food="lasagna")
@@ -148,8 +149,16 @@ None is None # => True
# very useful when dealing with primitive values, but is
# very useful when dealing with objects.
-# None, 0, and empty strings/lists all evaluate to False.
-# All other values are True
+# Any object can be used in a Boolean context.
+# The following values are considered falsey:
+# - None
+# - zero of any numeric type (e.g., 0, 0L, 0.0, 0j)
+# - empty sequences (e.g., '', (), [])
+# - empty containers (e.g., {}, set())
+# - instances of user-defined classes meeting certain conditions
+# see: https://docs.python.org/2/reference/datamodel.html#object.__nonzero__
+#
+# All other values are truthy (using the bool() function on them returns True).
bool(0) # => False
bool("") # => False
@@ -238,7 +247,7 @@ li.remove(2) # Raises a ValueError as 2 is not in the list
li.insert(1, 2) # li is now [1, 2, 3, 4, 5, 6] again
# Get the index of the first item found
-li.index(2) # => 3
+li.index(2) # => 1
li.index(7) # Raises a ValueError as 7 is not in the list
# Check for existence in a list with "in"
@@ -261,8 +270,9 @@ tup[:2] # => (1, 2)
# You can unpack tuples (or lists) into variables
a, b, c = (1, 2, 3) # a is now 1, b is now 2 and c is now 3
+d, e, f = 4, 5, 6 # you can leave out the parentheses
# Tuples are created by default if you leave out the parentheses
-d, e, f = 4, 5, 6
+g = 4, 5, 6 # => (4, 5, 6)
# Now look how easy it is to swap two values
e, d = d, e # d is now 5 and e is now 4