Skip to main content
Engineering LibreTexts

10.4: Dictionaries and Tuples

  • Page ID
    3173
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)

    Dictionaries have a method called items that returns a list of tuples, where each tuple is a key-value pair:

    >>> d = {'a':10, 'b':1, 'c':22}
    >>> t = list(d.items())
    >>> print(t)
    [('b', 1), ('a', 10), ('c', 22)]

    As you should expect from a dictionary, the items are in no particular order.

    However, since the list of tuples is a list, and tuples are comparable, we can now sort the list of tuples. Converting a dictionary to a list of tuples is a way for us to output the contents of a dictionary sorted by key:

    >>> d = {'a':10, 'b':1, 'c':22}
    >>> t = list(d.items())
    >>> t
    [('b', 1), ('a', 10), ('c', 22)]
    >>> t.sort()
    >>> t
    [('a', 10), ('b', 1), ('c', 22)]

    The new list is sorted in ascending alphabetical order by the key value.


    This page titled 10.4: Dictionaries and Tuples is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Chuck Severance.

    • Was this article helpful?