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一、字典的常見用法
1、創建字典
① 創建非空字典
dict = {"name": "賀增增" , "idol": "許嵩", "time": "13"}
② 創建空字典
dict = {}
2、對字典中元素做修改
① 對key爲"time"的值進行修改,若字典中若沒有該key,則創建該鍵值;
dict["time"] = 100
② 對key爲"idol"的值進行刪除
dict.pop("idol")
3、字典的遍歷
① 默認按鍵名進行遍歷,得到以鍵形式的輸出
for a in dict:
print(a)
② 和①的結果一樣,得到以鍵形式的輸出
for b in dict.keys():
print(b)
③ 按值進行遍歷,得到以值形式的輸出
for b in dict.values():
print(b)
④ 按鍵值對進行遍歷,得到以元組形式的輸出
for c in dict.items():
print(c)
⑤ 按鍵值對進行遍歷,得到以鍵名和鍵值的輸出
for k,v in dict.items():
print(k,v)
二、List的常見用法
1、創建list
① 創建非空list
list = ["賀增增", "許嵩", "許嵩N代弟子"]
② 創建空字典
list = []
2、對字典中元素做修改
① 爲字典增加元素;
#方式一 append() 追加單個元素到list的尾部
music = ["如果當時", "灰色頭像", "如約而至"]
list.append(music)
print(list)
output:["賀增增", "許嵩", "許嵩N代弟子", [“如果當時”, "灰色頭像", "如約而至"]]
#方式二 extend() 將一個列表中每個元素分別添加到另一個列表中
music = ["如果當時", "灰色頭像", "如約而至"]
list.extend(music)
print(list)
output:["賀增增", "許嵩", "許嵩N代弟子", "如果當時", "灰色頭像", "如約而至"]
#方式三 insert() 將一個元素插入到列表中
list.insert(1,'薛之謙')
print(list)
output:["賀增增", "薛之謙", "許嵩", "許嵩N代弟子"]
#方式四 + 加號,將兩個list相加,會返回到一個新的list對象。
album = [”夢遊計“, ”青年晚報“]
list_new = list + album
print(list_new)
output:["賀增增", "薛之謙", "許嵩", "許嵩N代弟子", ”夢遊計“, ”青年晚報“]
注:方法四與前三種方法的區別,前面三種方法(append, extend, insert)可對列表增加元素的操作,它們沒有返回值,是直接修改了原數據對象。 而方法四是將兩個list相加,需要創建新的list對象,從而需要消耗額外的內存,特別是當list較大時,儘量不要使用“+”來添加list,而應該儘可能使用List的append()方法。
② 對list的值進行刪除
#方式一 remove() 刪除指定位置的元素
list.remove(2)
print(list)
output:["賀增增", "許嵩N代弟子"]
#方式二 del list[*] 刪除指定元素
del list[0]
print(list)
output:["許嵩", "許嵩N代弟子"]
#方式三 pop(1) 彈出指定倒數位置的元素(默認最後一個元素)
list.pop()
print(list)
output:["賀增增", "許嵩"]
3、列表的遍歷
#方法一
for i in list:
print ("序號:%s 值:%s" % (list.index(i) + 1, i))
#方法二
for i in range(len(list)):
print ("序號:%s 值:%s" % (i + 1, list[i]))
#方法三
for i, val in enumerate(list):
print ("序號:%s 值:%s" % (i + 1, val))
#方法四
for i, val in enumerate(list, 2):
print ("序號:%s 值:%s" % (i + 1, val))
三、txt文本的常見讀取方式
1、按行讀取(with讀取)
with open(filename, 'r', encoding='UTF-8') as f:
lines = f.readlines()
2、按行讀取(普通讀取)
# 打開文件,循環讀取
lines = open(filename, 'r')
for line in lines:
print(line)
2、按列讀取(df方式)
# 導入數據
df = pd.read_csv("./data/all_available_features.txt", sep='\001', header=0)
# 將數據按列讀取
df.columns = ["unionid", "gender", "big_room", "big_room_ratio", "single_room", "single_room_ratio",
"standard_room", "standard_room_ratio", "family_room", "family_room_ratio", "superior_room",
"superior_room_ratio", "other_room", "other_room_ratio", "all_room", "summer_holiday",
"summer_holiday_ratio", "winter_holiday", "winter_holiday_ratio", "minor_holiday",
"minor_holiday_ratio", "weekend_holiday", "weekend_holiday_ratio", "other_holiday",
"other_holiday_ratio", "mem_basic", "mem_outgoing", "mem_marriage", "mem_education",
"mem_certification", "mem_stayArea", "mem_stayCity", "mem_age", "mem_sex", "mem_assets",
"mem_constellation", "mem_social_stratum", "mem_area", "mem_city", "mem_career",
"mem_birthday", "mem_mail", "label"]
# 以ndarray格式按行存儲,X的一行代表一個樣本
X = df[["gender", "big_room", "big_room_ratio", "single_room", "single_room_ratio",
"standard_room", "standard_room_ratio", "family_room", "family_room_ratio", "superior_room",
"superior_room_ratio", "other_room", "other_room_ratio", "all_room", "summer_holiday",
"summer_holiday_ratio", "winter_holiday", "winter_holiday_ratio", "minor_holiday",
"minor_holiday_ratio", "weekend_holiday", "weekend_holiday_ratio", "other_holiday",
"other_holiday_ratio", "mem_basic", "mem_outgoing", "mem_marriage", "mem_education",
"mem_certification", "mem_stayArea", "mem_stayCity", "mem_age", "mem_sex", "mem_assets",
"mem_constellation", "mem_social_stratum", "mem_area", "mem_city", "mem_career",
"mem_birthday", "mem_mail"]]
X = np.array(X)
四、時間間隔的常見計算方式
1、調用datetime庫進行計算時間間隔
def compare_time(time1, time2):
d1 = datetime.datetime.strptime(time1, '%Y-%m-%d')
d2 = datetime.datetime.strptime(time2, '%Y-%m-%d')
delta = d1 - d2
print("days is:{}".format(delta.days))
if delta.days >= 0:
return delta.days
else:
return -1
2、對只包含時間元素的list進行排序
#list_Data將所有的time(如:2015-10-01)存儲起來
list_Data.append(time)
#對只包含時間元素的list_Data進行升序排序
sorted(list_Data, key=lambda date: datetime.datetime.strptime(date, '%Y-%m-%d').timestamp())
日積月累,與君共進,增增小結,未完待續。