从二进制文件读取多行

Question

I have a binary file, and I want to read its content, Here's the code

with open ('file1', 'rb') as fp:

itemlist = pickle.load(fp)
print(itemlist)

and the code I am using to write to the file is

with open('file1', 'ab') as fp:

pickle.dump(training, fp)

The file contains many length 4 lists. The problem is print(itemlist) is just printing the last list while I want all of them to convert to 2-D numpy array.I can even see the file size increasing gradually with every append call.

How can I do it?

Answer 1

If you have many length 4 lists, you should dump and load them as a list of length 4 lists. Otherwise you would have to call pickle.load repeatedly until the file is exhausted.

Answer 2

Build the 2d list first and after you save it. In this way, you don't need to write/read multiple times the file.

For example:

   import pickle
   training = []

   list1 = [2,4,5,6,7,7,2,6]
   list2 = [5,6,53,6,75,3,53,65]
   list3 = [46,89,24,64,243,25,6]
   list4 = [78,875,24,24,64,363,25]

   training.append(list1)
   training.append(list2)
   training.append(list3) 
   training.append(list4)

   with open('file1', 'ab') as fp:
       pickle.dump(training, fp)


   with open ('file1', 'rb') as fp:
      itemlist = pickle.load(fp)
      print(itemlist)

The output:

  [[2,4,5,6,7,7,2,6], [5,6,53,6,75,3,53,65], [46,89,24,64,243,25,6], [78,875,24,24,64,363,25]]