CODEWITHSUNDEEP
python-3.xordereddictionary
Davtho1983
Davtho1983

Reputation: 3954

Need help understanding behaviour of Ordereddict

I have an ordered dictionary of days of the week:

weekdays = collections.OrderedDict([ ('Mon', 0), ('Tue', 0), ('Wed', 0), ('Thu', 0), ('Fri', 0), ('Sat', 0), ('Sun', 0) ])

I want to change the nth key's value to 1, so if I set n to 4, the 4th key is 'Thu' so weekdays becomes:

OrderedDict([('Mon', 0), ('Tue', 0), ('Wed', 0), ('Thu', 1), ('Fri', 0), ('Sat', 0), ('Sun', 0)])

I can do that with the following code:

startday_2017 = 4
weekdays = collections.OrderedDict([ ('Mon', 0), ('Tue', 0), ('Wed', 0), ('Thu', 0), ('Fri', 0), ('Sat', 0), ('Sun', 0) ])
date = list(weekdays.keys())[(startday_2017-1)]
for key in weekdays.keys():
        if key == date:
            weekdays[key] = 1

That seems to work, but if I want to change the values corresponding to keys before or after the nth key, the ordereddict starts acting funny. With this code:

startday_2017 = 4
weekdays = collections.OrderedDict([ ('Mon', 0), ('Tue', 0), ('Wed', 0), ('Thu', 0), ('Fri', 0), ('Sat', 0), ('Sun', 0) ])
date = list(weekdays.keys())[(startday_2017-1)]
for key in weekdays.keys():
        if key < date:
            weekdays[key] = "applesauce"
        elif key == date:
            weekdays[key] = 1
        else:
            weekdays[key] = 2

print(weekdays)

I get this output:

OrderedDict([('Mon', 'applesauce'), ('Tue', 2), ('Wed', 2), ('Thu', 1), ('Fri', 'applesauce'), ('Sat', 'applesauce'), ('Sun', 'applesauce')])

How do I achieve the result I'm after?

Upvotes: 0

Views: 35

Answers (1)

AChampion
AChampion

Reputation: 30258

Because you are doing lexical comparison not numerical ordering, 'Tue' > 'Thurs':

What you might want to try is just to enumerate() the keys and use the numerical value, e.g.:

In []:
for i, key in enumerate(weekdays, 1):
    if i < startday_2017:
        weekdays[key] = "applesauce"
    elif i == startday_2017:
        weekdays[key] = 1
    else:
        weekdays[key] = 2
weekdays

Out[]:
OrderedDict([('Mon', 'applesauce'),
             ('Tue', 'applesauce'),
             ('Wed', 'applesauce'),
             ('Thu', 1),
             ('Fri', 2),
             ('Sat', 2),
             ('Sun', 2)])

Upvotes: 1

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