python常用的小東西

防止忘記，在此做個記錄

目錄：

1.  讀取csv
2. 篩選
3. 排序

1.讀取csv

import pandas as pd
file = pd.read_csv(r'D:\projects\PycharmProjects\final_wangwei\final_news_all.csv', usecols=['entity_id', 'post_title','publish_year','publish_month'])

2.根據列值篩選

news=file[((file['publish_year']==2018) & (file['publish_month']>4))|((file['publish_year']==2019) & (file['publish_month']<5))]

3.根據某列值排序（升序）

news=news.sort_values('publish_month',ascending=True)

4.對於pandas.core.frame.DataFrame提取某列，並轉換爲list

news['entity_id'].values.tolist()

5.根據某列統計

news['publish_month'].value_counts()

6.讀取txt，concat

df_empty = pd.DataFrame(columns=['doc'])
data1=pd.read_csv('linshi/5079161.txt',names=["doc"])

df=pd.concat([df_empty,data1,data2,data3,data4],axis=0)  #縱向

7.獲取當前時間

import time

 print(time.strftime('%Y-%m-%d %H:%M:%S',time.localtime(time.time())))

8.按行創建dataframe

sdp=pd.DataFrame.from_items([('months',months),('shoucangs',shoucangs),('dianzans',dianzans),('pingluns',pingluns)])