From 07dc91800f1b379f2c6a46cc1db1b221f202ea4d Mon Sep 17 00:00:00 2001 From: Raymond Hettinger Date: Tue, 25 Jun 2002 15:13:18 +0000 Subject: Close bug 480337: Dict used before dicts explained. Added explanation and examples of the dict() constructor. --- Doc/tut/tut.tex | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex index 0dc53ef..0a4c95e 100644 --- a/Doc/tut/tut.tex +++ b/Doc/tut/tut.tex @@ -1843,8 +1843,6 @@ parenthesized. [12, 18] >>> [3*x for x in vec if x < 2] [] ->>> [{x: x**2} for x in vec] -[{2: 4}, {4: 16}, {6: 36}] >>> [[x,x**2] for x in vec] [[2, 4], [4, 16], [6, 36]] >>> [x, x**2 for x in vec] # error - parens required for tuples @@ -2023,6 +2021,17 @@ Here is a small example using a dictionary: 1 \end{verbatim} +The \function{dict()} contructor builds dictionaries directly from +lists of key-value pairs stored as tuples. When the pairs form a +pattern, list comprehensions can compactly specify the key-value list. + +\begin{verbatim} +>>> dict([('sape', 4139), ('guido', 4127), ('jack', 4098)]) +{'sape': 4139, 'jack': 4098, 'guido': 4127} +>>> dict([(x, x**2) for x in vec]) # use a list comprehension +{2: 4, 4: 16, 6: 36} +\end{verbatim} + \section{Looping Techniques \label{loopidioms}} -- cgit v0.12