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java and python equivalent of php's foreach($array as $key => $value)

Asked 2009-08-02T19:02:46.430
15

In php, one can handle a list of state names and their abbreviations with an associative array like this:

<?php
    $stateArray = array(
        "ALABAMA"=>"AL",
        "ALASKA"=>"AK",
        // etc...
        "WYOMING"=>"WY"
    );

    foreach ($stateArray as $stateName => $stateAbbreviation){
        print "The abbreviation for $stateName is $stateAbbreviation.\n\n";
    }
?>

Output (with key order preserved):

The abbreviation for ALABAMA is AL.

The abbreviation for ALASKA is AK.

The abbreviation for WYOMING is WY.

EDIT: Note that the order of array elements is preserved in the output of the php version. The Java implementation, using a HashMap, does not guarantee the order of elements. Nor does the dictionary in Python.

How is this done in java and python? I only find approaches that supply the value, given the key, like python's:

stateDict = {
    "ALASKA": "AK",
    "WYOMING": "WY",
}

for key in stateDict:
    value = stateDict[key]

EDIT: based on the answers, this was my solution in python,

# a list of two-tuples
stateList = [
    ('ALABAMA', 'AL'),
    ('ALASKA', 'AK'),
    ('WISCONSIN', 'WI'),
    ('WYOMING', 'WY'),
]

for name, abbreviation in stateList:
    print name, abbreviation

Output:

ALABAMA AL
ALASKA AK
WISCONSIN WI
WYOMING WY

Which is exactly what was required.

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1 Answer

1

Along the lines of Alexander's answer...

The native python dictionary doesn't maintain ordering for maximum efficiency of its primary use: an unordered mapping of keys to values.

I can think of two workarounds:

  1. look at the source code of OrderedDict and include it in your own program.

  2. make a list that holds the keys in order:

    states = ['Alabamba', 'Alaska', ...]  
    statesd = {'Alabamba':'AL', 'Alaska':'AK', ...}
    for k in states:
        print "The abbreviation for %s is %s." % (k, statesd[k])
    
answered 2009-08-02T21:57:32.267

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