os.listdir 没有读取所有文件

Question

I am trying to pull a particular line out of each file within a folder. The code I wrote is opening each file and opening the new output file, although it is looping within each file and outputting data twice in some cases. I have 15 files within about 800,000 lines between all files.

`import os
    for filename in os.listdir("path"):
       fin=open("path\%s" %filename)
       #print fin
       fout=open("newdata.txt","w")
       #print fout
       l=""
       for line in fin:
           p=line.strip().split("\t")
           if p[3]=="Cycle" and p[4]=="Protein":
               l+=line
              fout.write(l)
       #else:pass
  # fin.close()
  # fout.close()`

Answer 1

您在循环中以“w”模式打开文件，因此对于每个新文件，它将从头开始输出文件，您应该在循环外打开它或使用“w+”模式