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| -rw-r--r-- | Doc/tut/tut.tex | 13 |
1 files 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}} |