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一、字典的常见用法
1、创建字典
① 创建非空字典
dict = {"name": "贺增增" , "idol": "许嵩", "time": "13"}
② 创建空字典
dict = {}
2、对字典中元素做修改
① 对key为"time"的值进行修改,若字典中若没有该key,则创建该键值;
dict["time"] = 100
② 对key为"idol"的值进行删除
dict.pop("idol")
3、字典的遍历
① 默认按键名进行遍历,得到以键形式的输出
for a in dict:
print(a)
② 和①的结果一样,得到以键形式的输出
for b in dict.keys():
print(b)
③ 按值进行遍历,得到以值形式的输出
for b in dict.values():
print(b)
④ 按键值对进行遍历,得到以元组形式的输出
for c in dict.items():
print(c)
⑤ 按键值对进行遍历,得到以键名和键值的输出
for k,v in dict.items():
print(k,v)
二、List的常见用法
1、创建list
① 创建非空list
list = ["贺增增", "许嵩", "许嵩N代弟子"]
② 创建空字典
list = []
2、对字典中元素做修改
① 为字典增加元素;
#方式一 append() 追加单个元素到list的尾部
music = ["如果当时", "灰色头像", "如约而至"]
list.append(music)
print(list)
output:["贺增增", "许嵩", "许嵩N代弟子", [“如果当时”, "灰色头像", "如约而至"]]
#方式二 extend() 将一个列表中每个元素分别添加到另一个列表中
music = ["如果当时", "灰色头像", "如约而至"]
list.extend(music)
print(list)
output:["贺增增", "许嵩", "许嵩N代弟子", "如果当时", "灰色头像", "如约而至"]
#方式三 insert() 将一个元素插入到列表中
list.insert(1,'薛之谦')
print(list)
output:["贺增增", "薛之谦", "许嵩", "许嵩N代弟子"]
#方式四 + 加号,将两个list相加,会返回到一个新的list对象。
album = [”梦游计“, ”青年晚报“]
list_new = list + album
print(list_new)
output:["贺增增", "薛之谦", "许嵩", "许嵩N代弟子", ”梦游计“, ”青年晚报“]
注:方法四与前三种方法的区别,前面三种方法(append, extend, insert)可对列表增加元素的操作,它们没有返回值,是直接修改了原数据对象。 而方法四是将两个list相加,需要创建新的list对象,从而需要消耗额外的内存,特别是当list较大时,尽量不要使用“+”来添加list,而应该尽可能使用List的append()方法。
② 对list的值进行删除
#方式一 remove() 删除指定位置的元素
list.remove(2)
print(list)
output:["贺增增", "许嵩N代弟子"]
#方式二 del list[*] 删除指定元素
del list[0]
print(list)
output:["许嵩", "许嵩N代弟子"]
#方式三 pop(1) 弹出指定倒数位置的元素(默认最后一个元素)
list.pop()
print(list)
output:["贺增增", "许嵩"]
3、列表的遍历
#方法一
for i in list:
print ("序号:%s 值:%s" % (list.index(i) + 1, i))
#方法二
for i in range(len(list)):
print ("序号:%s 值:%s" % (i + 1, list[i]))
#方法三
for i, val in enumerate(list):
print ("序号:%s 值:%s" % (i + 1, val))
#方法四
for i, val in enumerate(list, 2):
print ("序号:%s 值:%s" % (i + 1, val))
三、txt文本的常见读取方式
1、按行读取(with读取)
with open(filename, 'r', encoding='UTF-8') as f:
lines = f.readlines()
2、按行读取(普通读取)
# 打开文件,循环读取
lines = open(filename, 'r')
for line in lines:
print(line)
2、按列读取(df方式)
# 导入数据
df = pd.read_csv("./data/all_available_features.txt", sep='\001', header=0)
# 将数据按列读取
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格式按行存储,X的一行代表一个样本
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、时间间隔的常见计算方式
1、调用datetime库进行计算时间间隔
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、对只包含时间元素的list进行排序
#list_Data将所有的time(如:2015-10-01)存储起来
list_Data.append(time)
#对只包含时间元素的list_Data进行升序排序
sorted(list_Data, key=lambda date: datetime.datetime.strptime(date, '%Y-%m-%d').timestamp())
日积月累,与君共进,增增小结,未完待续。