Name | Dictionary |
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Examples |
# Create a new dictionary element_names = {'H': 'hydrogen', 'He': 'helium', 'Li': 'lithium'} # Add another key/value pair to the dictionary element_names['Be'] = 'beryllium' element_names['B'] = 'boron' element_names['C'] = 'carbon' # Loop over elements of dictionary. Note that key/value pairs # are returned in an arbitrary order! for k, v in element_names.iteritems(): print("symbol: " + k + "; name: " + v) # Get an individual value by key print(element_names['He']) # Prints 'helium' # Delete an item from a dictionary del element_names['C'] # Keys don't have to be strings! They can be of any (hashable) # type. Values can also be of any type. number_map = { 1: [0.5, 1.0, 2.0], 2: [10.0, 15.0, 20.0], 3: [50.0, 75.0, 100.0] } print(number_map[2]) # Prints [10.0, 15.0, 20.0] | ||||||||||
Description |
A dictionary is a Python data structure that stores a number of values,
referenced by key. It's similar to a list, except values are accessed by keys
of arbitrary types (usually strings), instead of with sequential integer
indexes. Python's dictionary type is similar to "Maps" in Java, associative
arrays in PHP, or hashes in Perl. In Python, dictionary values can be of any type (and types can vary from one key/value pair to the next in the same dictionary). Keys can be of any type, as long as that type is "hashable" (see the Python glossary for more information). Note that while Python remembers all key/value pairs added to a dictionary, it does not remember the order in which key/value pairs were added. As a consequence, when iterating over key/value pairs in a dictionary (with, e.g., the iteritems() method shown in the example above), the key/value pairs will come back in an arbitrary order, which may vary from one execution of your program to the next. |
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Syntax | d = {} d = dict() d = {key: value, key2: value} | ||||||||||
Parameters |
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Methods |
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Related |
{} (Curly braces) [] (Index brackets) |
Updated on Tue Feb 27 14:07:12 2024.
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