Python: Copying lines that meet requirements -

so, basically, need program opens .dat file, checks each line see if meets prerequisites, , if do, copy them new csv file.

the prerequisites must 1) contain "$w" or "$s" , 2) have last value @ end of line of dat 1 of long list of acceptable terms. (i can make-up list of terms , hardcode them list)

for example, if csv list of purchase information , last item purchased, want include fruit. in case, last item id tag, , want accept handful of id tags, there list of 5 acceptable tags. tags have veriable length, however, last item in list (and 4th item on list)

let me give better example, again fruit.

my original .dat might be:

dgh$g$h $2.53 london_port gyro  dgh.$wfft$q5632 $33.54 55n39 barkdust  uykj$s.52ue $23.57 22#3 apple  wsiajsm_33$4.fj4 $223.4 ha25%ek banana 

only line: "uykj$s $23.57 22#3 apple" copied because has both 1) $w or $s (in case $s) , 2) last item fruit. once .csv file made, going need go through , replace spaces commas, that's not problematic me figuring out how scan each line requirements , copy ones wanted.

i making few programs similar one, open .dat files, check each line see if meet requirements, , decides copy them new file or not. sadly, have no idea doing. similar enough once figure out how make one, rest easy, though.

edit: .dat files few thousand lines long, if matters @ all.

edit2: of current code snippets

right now, current version this:

def main():     #newfile_loc = c:\users\j18509\documents     oldfile_loc=raw_input("input file mclg:")     oldfile = open(oldfile_loc,"r")     oldtext = oldfile.read() #   in range(0, len(oldtext)): #       if (oldtext[i] != " "): #           print oldtext[i]     = split_line(oldtext)     if u'$s' in i:         # $s in line         print main() 

but it's choppy still. i'm learning python.

brief update: server working on down, , might next few hours, have new code, has syntax errors in it, here anyways. i'll update again once working. bunch everyone!

import os newfilepath = "a:\test.txt" acceptable_values = ('apple','banana') #main def main():     if os.path.isfile(newfilepath):         os.remove(newfilepath)     newfile = open (newfilepath, 'w')     newfile.write('header 1,','name header,','header 3,','header 4)     oldfile_loc=raw_input("input file program:")     oldfile = open(oldfile_loc,"r")     line in oldfile:         lineparts = line.split()         if (lineparts[0].find($w)) or (lineparts[0].find($s)):             if lineparts[3] in acceptable_values:                 print(lineparts[1], ' accepted')                 #this line acceptable!                 newfile.write(lineparts[1],',',lineparts[0],',',lineparts[2],',',lineparts[3])     oldfile.close()     newfile.close() main() 

there 2 parts need implement: first, read file line line , write lines meeting specific criteria. done by

with open('file.dat') f:     line in f:         stripped = line.strip() # remove '\n' end of line         if test_line(stripped):             print stripped # write stdout 

the criteria want check implemented in function test_line. check occurrence of "$w" or "$s", can use in-operator like

if not '$w' in line , not '$s' in line:     return false else:     return true 

to check, if last item in line contained in fixed list, first split line using split(), take last item using index notation [-1] (negative indices count end of sequence) , use in operator again against fixed list. looks like

items = line.split() # items array of strings last_item = items[-1] # take last element of array if last_item in ['apple', 'banana']:     return true else:     return false 

now, combine these 2 parts test_line function like

def test_line(line):     if not '$w' in line , not '$s' in line:         return false     items = line.split() # items array of strings     last_item = items[-1] # take last element of array     if last_item in ['apple', 'banana']:         return true     else:         return false 

note program writes result stdout, can redirect. if want write output file, have @ correct way write line file in python