python - 在 python 3 中读取和写入文件

Question

import os.path

endofprogram=False
try:

   filename1=input("Enter input file: ")
   filename2=input("Enter output file: ")

   while os.path.isfile(filename2):
       filename2=input("File Exists! Enter new name for output file: ") 

except IOError:
   print("Error opening file - End of program")
   endofprogram=True

if(endofprogram == False):
   infile=open(filename1, "r")
   content=infile.read()
   lines=[]
   words=[]

   lines=content.split('\n')
   print("Total animals=",len(lines))  

多年来我一直在研究这个与文件有关的程序。我有一个文件:

#color     size    flesh     class
brown     large    hard      safe
green     large    hard      safe
red       large    soft      dangerous
green     large    soft      safe


red       small    hard      safe
red       small    hard      safe
brown     small    hard      safe
green     small    soft      dangerous
green     small    hard      dangerous
red       large    hard      safe
brown     large    soft      safe
green     small    soft      dangerous
red       small    soft      safe
red       large    hard      dangerous
red       small    hard      safe
green     small    hard      dangerous 

我应该回答以下问题:

• 动物总数？
• 危险动物总数？
• 安全的大型动物数量？

到目前为止，我可以打印出动物的总数，但它包括空格以及我不想要的注释行。目前对于动物总数，打印的是 19，而应该是 16。我不知道从哪里开始回答后面的两个问题。

Answer 1

你应该逐行处理文件，这比读取整个文件更容易，比如:

infile = open('entrada', 'r')

animals = 0
safe_animals = 0
dangerous_animals = 0

for line in infile:
    line_components = line.strip().split()
    if line_components:
        animals += 1

        if line_components[3] == 'dangerous':
            dangerous_animals += 1
        elif line_components[3] == 'safe' and line_components[1] == 'large':
            safe_animals += 1

print "%i animals" % animals
print "%i safe animals" % safe_animals
print "%i dangerous animals" % dangerous_animals