读取文件，删除文本字段，保留数字字段

Question

我想写一个小的python脚本来绘制一些.dat文件。为此，我需要先处理文件。.dat文件如下所示：

(Real64
 (numDims 1)
 (size 513)
 (data 
   [ 90.0282291905089 90.94377050431068 92.31708247501335 93.38521400778211 94.60593575951782 95.67406729228657 97.04737926298925 97.96292057679104 ...]
 )
)

我想删除文本部分和"普通"括号。我只需要介于 [.....] 之间的数据。

我尝试了这样的事情：

from Tkinter import Tk
from tkFileDialog import askopenfilename
# just a small GUI to get the file
Tk().withdraw()
filename = askopenfilename()
import numpy as np
with open(filename) as f:
    temp = f.readlines(5) #this is the line in the .dat file
    for i in range(len(temp)-1):
        if type(temp[i]) == str:
            del temp[i]

然而，这总是导致"出界指数"。帮助将不胜感激。

Answer 1

我只需要介于 [.....] 之间的数据

# treat the whole thing as a string
temp = '''(Real64
 (numDims 1)
 (size 513)
 (data
   [ 90.0282291905089 90.94377050431068 92.31708247501335 ]
 )
)'''
# split() at open bracket; take everything right
# then split() at close bracket; take everything left
# strip() trailing / leading white space
number_string = temp.split('[')[1].split(']')[0].strip()
# convert to list of floats, because I expect you'll need to
number_list = [float(i) for i in number_string.split(' ')]
print number_string
print number_list
>>> 90.0282291905089 90.94377050431068 92.31708247501335
>>> [90.0282291905089, 90.94377050431068, 92.31708247501335]

Answer 2

print re.findall("[([0-9. ]+)]",f.read())

这称为regular expression，它说找到我所有的东西，即两个方括号之间的数字句点和空格

 [   # literal left bracket
 ( # capture the stuff in here
 [0-9. ] # accept 0-9 and . and space
+ # at least one ... probably more
 ) # end capture group
 ] # literal close bracket

或者，您可以使用类似pyparsing的东西

inputdata = '''(Real64
 (numDims 1)
 (size 513)
 (data
   [ 90.0282291905089 90.94377050431068 92.31708247501335 93.38521400778211 94.60593575951782 95.67406729228657 97.04737926298925 97.96292057679104 ...]
 )
)
'''
from pyparsing import OneOrMore, nestedExpr
data = OneOrMore(nestedExpr()).parseString(inputdata)
print "GOT:", data[0][-1][2:-1]