udict.md

UDict

Introduction

UDict is class which is simplifying working with Python dicts. It has many methods, properties, magic methods.

Firstly, import UDict from ufpy

from ufpy import UDict

Create UDict

For creating UDict you should use this code:

d = UDict({'id': 2, 'content': 'hello, world'})
# for string keys you can use this way:
d = UDict(id=2, content='hello, world')

You can also define default value for items when you use item's getter:

d = UDict(id=2, content='hello, world', default=0)

Get items

For getting items you should use the way you use in lists and dicts: use UDict[key] syntax:

d['id'] # 2

You can also use index of key or slice of indexes of keys:

Caution

In this class first index is 1

d[1] # 2
d[:] # u{'id': 2, 'content': 'hello, world'} (UDict object)

You can also use get() method. You can get item by its key using key kwarg, you can get item by its index using index kwarg, and you get item key by its value using value kwarg.

Also you can define default only for this calling of get() using default kwarg.

Example:

d = UDict({2: 3, 1: 4}, default=None)
d[2] # 3
d.get(index=2) # 4
d.get(key=1) # also 4
d.get(value=3) # 2

d.get(key=3) # None
d.get(key=3, default='null') # 'null'

Set items

For setting items you should use the way you use in lists and dicts: use UDict[key] = value syntax:

d['id'] = 3

Also, you can use indexes and slices when you are setting items:

d[1] = 2
d[2:6:2] = 8
d[:3] = 1, 2, 3

Delete items

For deleting items you should use the way you use in lists and dicts: use del UDict[key] syntax:

del d['id']

Also, you can use indexes and slices:

del d[1]
del d[:] # all UDict will become empty

Get length of dict

You can get length of dict using inbuilt len() function

d = UDict(hello=1, hi=2)
len(d) # 2

Iterate dict: keys, values, items properties

You can iterate dict using for key, value in UDict syntax.

d = UDict(hello=1, hi=2)
for key, value in d:
    print(key, value)
    
# out:
#
# hello 1
# hi 2

Also, you can iterate items property for this result

for key, value in d.items:
    ...

If you want iterate only all keys or values, use keys or values properties

for key in d.keys:
    ...

for value in d.values:
    ...

Check that dict is empty or not empty

You can use is_empty() method to check that UDict is empty:

d = UDict()
print(d.is_empty()) # True

d['hello'] = 'world'
print(d.is_empty()) # False

You also can use if UDict or bool(UDict) syntax:

d = UDict()
print(bool(d)) # False

d['hello'] = 'world'
print(bool(d)) # True

if d:
    print('True!')

# out: True!

Check that key or item in dict

You can check that key in dict:

d = UDict(hi=1, hello=2)

print('hi' in d) # True
print('hii' in d) # False

You can also check that item in dict:

d = UDict(hi=1, hello=2)

print(('hi', 1) in d) # True
print(('hi', 11) in d) # False

Using repr() and print()

Since print() uses repr(), you can directly print UDict objects.

d = UDict(hi=1, hello=2)
print(d) # u{'hi': 1, 'hello': 2}
print(repr(d)) # u{'hi': 1, 'hello': 2}

Comparing dicts

You can compare UDicts using inbuilt compare operators (==, !=, >, >=, <, <=):

Note

When you use equal and not equal compare operator, dicts are comparing by its items and length, but in other compare operators dicts are comparing only by its length.

For example, d > d2 -> len(d) > len(d2), etc.

d = UDict(hi=1, hello=2)
d2 = UDict(hi=1, hello=2)
d3 = UDict(hi=1, hello=2, world=3)

print(d == d2) # True
print(d != d2) # False
print(d < d3) # True
print(d <= d3) # True
print(d3 > d) # True
print(d3 >= d) # True

Math operations

You can use inbuilt math operators (+, -, *, /, +=, -=, *=, /=) with UDicts:

Note

When you use sum and sub math operators (+, -) dicts are summing or subtracting, but when you use other math operators dict will be multiplying or dividing by integer or dict.

When dict it works like this:

d * {'hello': 2, 'hi': 0.5}

d['hello'] * 2

d['hi'] * 0.5

d = UDict(hi=1, hello=2)
print(d + {'world': 3}) # u{'hi': 1, 'hello': 2, 'world': 3}
print(d - {'hello': 2}) # u{'hi': 1}

print(d * 2) # u{'hi': 2, 'hello': 4}
print(d * {'hi': 2}) # u{'hi': 2, 'hello': 2}

print(d / 2) # u{'hi': 0.5, 'hello': 1}
print(d / {'hi': 2}) # u{'hi': 0.5, 'hello': 2}

Negative dict

You can use unary minus with dicts:

d = UDict(hi=1, hello=2)
print(-d) # u{'hi': -1, 'hello': -2}

Reverse dict

You can reverse dict using reverse() or reversed() method.

Caution

When you use reverse(), dict updates in contrast to reversed(). Be careful!

# reverse()
d = UDict(b=1, a=2)
print(d.reverse()) # u{'a': 2, 'b': 1}
print(d) # u{'a': 2, 'b': 1}

# reversed()
d = UDict(b=1, a=2)
print(d.reversed()) # u{'a': 2, 'b': 1}
print(d) # u{'b': 1, 'a': 2}

d.reverse()
d.reversed()

Also, you can use ~ operator and reversed() class. They are equivalents of UDict.reversed():

~d
reversed(d)

Sort dict

You can use sort() and sorted() methods for sorting UDict. sort() is updating dict, sorted() - isn't.

# sort()
d = UDict(b=1, a=2)
print(d.sort()) # u{'a': 2, 'b': 1}
print(d) # u{'a': 2, 'b': 1}

# sorted()
d = UDict(b=1, a=2)
print(d.sorted()) # u{'a': 2, 'b': 1}
print(d) # u{'b': 1, 'a': 2}