day07 finishing

day07 finishing

Shopping Cart structure

goods = goods_dic[goods_choice]
if  goods in goods_car:
    goods_car[goods] += 1
else :
    goods_car[goods] = 1

Tuple built-in method

What is a tuple: only desirable, can not change the list, create a tuple was written dead

effect

Creating a tuple was written dead

Defined way

(Spaced apart) within the plurality of elements with a comma (which may be of any data type)

Note: If only one element tuple must have a comma

Instructions

Index values

Index sliced

for loop

Member operator

len length

index acquisition element index

count count

Ordered or unordered

Ordered

dictionary

effect

Storing a plurality of data, each data having a description of

Defined way

{} The plurality of keys separated by commas key (descriptive sense, not the variable data), value (of any data type)

Variable == -> not hash, immutable -> == hashable

Instructions

#### in accordance with the key values

print(dic['b'])

Add value, not to modify

dic['b'] = 4

for loop

Member operator

len length

keys/values/items

for snf, sfkjjs in dic.items (): # unzip

​ print(snf,sfkjjs)

get

Obtain

update

Dictionary update overlay, increase

fromkeys

Get key value from the list, value is None

setdefault

Dictionary increase key, value

Disorderly

variable

set

What is the set is a collection of multiple data types (non-variable) consisting of a whole

effect

Calculates, and cross up

Deduplication

Out of order

Defined way

{} The plurality of elements separated by commas (not a variable data type)

Keyword set

Instructions

And |

cross&

Poor -

Complement ^

add()

Disorderly

variable

Data Type Summary

Number of stored-value

Save a value: plastic, floating point, character

A plurality of stored values: List / tuple / dictionary / collection

Order-disorder

Ordered: strings, lists, tuples

Disorder: dictionaries, collections

Variable immutable

Variable: lists, dictionaries, collections

Immutable: integer, floating point, string, a tuple

The main contents copy depth

Lt2 is 1. When the copy of the object lt1, immutable data changes within lt1, lt2 changes, changes in the internal lt1 variable data, variable lt2

Shallow copy

2. When lt2 is the copy of the object lt1, immutable data changes within lt1, lt2 does not change, changes within lt1 variable data, variable lt2

Deep copy

3. When the copy of the object is lt2 lt1 of immutable data changes within lt1, lt2 does not change, changes within lt1 variable data, unchanged lt2