Read and write Python CSV file

1.CSV file

ImportCsvwith Open (R"E:\code\0_DataSet\tianchi_2015_mobile_recommand\fresh_comp_offline\tianchi_fresh_comp_train_user.csv","r+") as Rdfile, open ("Data.csv","w+", newline="") as Wrfile:#WriteFile must open with newline+= "" or blank line would appear        #1 Create reader & writerCsvreader =Csv.reader (rdfile) Csvwriter=Csv.writer (wrfile)#2 Get the Headmost 10000 line and write to Wrfile         forLine,iinchZip (Csvreader,range (10001): Csvwriter.writerow (line)

CSV file Read and write:

　①open ()

The write must be newline= with the specified parameter ""

② Create reader () | Writer ()

Csv.reader ()

Csv.writer ()

③ Reading and writing

Without ReadLine read directly using the for line in Csvreader

Write using Csv.writer.writerow ()

2. Implementation of Str.replace ()

1) str.split () +str.jion (sequence)

1 def Mystrreplace (SRC,OLDSTR,NEWSTR): 2     return newstr.join (Src.split (OLDSTR))

2) Slicing + recursion

def Mystrreplace (SRC,OLDSTR,NEWSTR):     = Src.find (oldstr)    if pos = =-1        := src[:    ]else:         = src[:p os]+newstr+src[pos+len (oldstr):]        = mystrreplace (target,oldstr,newstr)     return Target

3. Python traverses the directory and prints the. PYc End of the file

1  fromOsImportWalk2  forRoot,dir,filesinchWalk"."):3     " "4 root,dir,files = Os.walk (top[, topdown=true[, onerror=none[, Followlinks=false]])5     " "6      forFileinchFiles:7         ifFile.endswith (". PYc"):8             Print(file)

Read and write Python CSV file