在python中研究具有可变数字的字符串

Question

I have a text file which contains several lines in the following format:

ELEMENT=      1 PLY=  1
-----------------------
 Code 1425                                    
    GP= 1  4.324E-03 -1.350E-03 -2.974E-03  3.084E-04  0.000E+00  0.000E+00
    GP= 2  1.435E-03 -3.529E-04 -1.082E-03  1.183E-04  0.000E+00  0.000E+00
    GP= 3  7.742E-03 -3.542E-03 -4.200E-03  4.714E-04  0.000E+00  0.000E+00
    GP= 4  4.842E-03 -2.378E-03 -2.463E-03  3.040E-04  0.000E+00  0.000E+00

The number after the word ELEMENT goes from 1 to 60. My first goal is to read this text file and stop to every occurrence of the word ELEMENT = 1 to ELEMENT = 60

My test script reads the first occurrence of ELEMENT . I would now like to go through the 60 occurrences of ELEMENT , so I have tried to implement a variable following ELEMENT , in this example I have initialized it to 2 to see if it would work and as you can guess it doesn't (see example code below).

elem= 2
lines = open("myfile.txt", "r" ).readlines()

for line in lines:
 if re.search( r"ELEMENT=      %i" (line, elem) ):
   words = line.split()

   energy = float( words[1] )

   print "%f" % energy
   break

I get the following error code:

File "recup.py", line 42, in <module>
if re.search( r"ELEMENT=      %i" (line, elem) ):
TypeError: 'str' object is not callable

My question then is how would I implement a variable into my search?

Answer 1

Just iterate over the blocks:

import re

txt='''\
ELEMENT=      1 PLY=  1
-----------------------
 Code 1425                                    
    GP= 1  4.324E-03 -1.350E-03 -2.974E-03  3.084E-04  0.000E+00  0.000E+00
    GP= 2  1.435E-03 -3.529E-04 -1.082E-03  1.183E-04  0.000E+00  0.000E+00
    GP= 3  7.742E-03 -3.542E-03 -4.200E-03  4.714E-04  0.000E+00  0.000E+00
    GP= 4  4.842E-03 -2.378E-03 -2.463E-03  3.040E-04  0.000E+00  0.000E+00

ELEMENT=      2 PLY=  22
-----------------------
 Code 1426                                 
    GP= 5  4.324E-03 -1.350E-03 -2.974E-03  3.084E-04  0.000E+00  0.000E+00
    GP= 6  1.435E-03 -3.529E-04 -1.082E-03  1.183E-04  0.000E+00  0.000E+00
    GP= 7  7.742E-03 -3.542E-03 -4.200E-03  4.714E-04  0.000E+00  0.000E+00
    GP= 8  4.842E-03 -2.378E-03 -2.463E-03  3.040E-04  0.000E+00  0.000E+00    
    '''

for i, m in enumerate(re.finditer(r'^ELEMENT=\s+(\d+.*?)(?=^ELEMENT|\Z)', txt, re.M | re.S)):
    print 'Group {}===:\n{}'.format(i, m.group(1))

This will find the blocks of lines stating with ELEMENT and ending either with the next block or the end of the file. Then parse the block found into whatever.

Prints:

Group 0===:
1 PLY=  1
-----------------------
 Code 1425                                    
    GP= 1  4.324E-03 -1.350E-03 -2.974E-03  3.084E-04  0.000E+00  0.000E+00
    GP= 2  1.435E-03 -3.529E-04 -1.082E-03  1.183E-04  0.000E+00  0.000E+00
    GP= 3  7.742E-03 -3.542E-03 -4.200E-03  4.714E-04  0.000E+00  0.000E+00
    GP= 4  4.842E-03 -2.378E-03 -2.463E-03  3.040E-04  0.000E+00  0.000E+00


Group 1===:
2 PLY=  22
-----------------------
 Code 1426                                 
    GP= 5  4.324E-03 -1.350E-03 -2.974E-03  3.084E-04  0.000E+00  0.000E+00
    GP= 6  1.435E-03 -3.529E-04 -1.082E-03  1.183E-04  0.000E+00  0.000E+00
    GP= 7  7.742E-03 -3.542E-03 -4.200E-03  4.714E-04  0.000E+00  0.000E+00
    GP= 8  4.842E-03 -2.378E-03 -2.463E-03  3.040E-04  0.000E+00  0.000E+00  

Answer 2

I'm not entirely sure what you're trying to do, but if you're trying to test which iteration of ELEMENT you're on, this would be a better way:

elem= 2
lines = open("myfile.txt", "r" ).readlines()

for line in lines:
  if re.match(r"ELEMENT=",line):
    words = line.split()
    if int(words[1]) == elem:
      # Do whatever you're trying to do.

Answer 3

If the line you search always starts with "ELEMENT" there is an easy way to work around this :

lines = open("myfile.txt", "r").readlines()
for line in lines:
  if line.startswith("ELEMENT"):
    words = line.split()
    print "ELEMENT : " + words[1] + ", PLY : " + words[3]

Using this you will print the line contents everytime you find an "ELEMENT" line. You can easily extract the "CODE" and "GP" line contents using the same trick ;).

Answer 4

a few simple changes:

elem= 2
lines = open("myfile.txt", "r" ).readlines()

for line in lines:
    words = line.split()
    if words[0].startswith('ELEMENT'):
        energy = int( words[1] )
        if energy == elem:
            break

print "%f" % energy
break

Don't try to compare == floats - it seldon turns out well

Answer 5

如果我正确理解了您的问题，您可以像这样将变量“植入”到搜索中：

if re.search( r"ELEMENT=      {}".format(elem), line ):