Question

Hi I have two text files that each contain different information about certain structures.The structures are identified in both files by an id number. What I would like to do is read in the first file and skip lines of data that do not meet a condition. Then have lines in the second file that do not have the same id number skipped and the others processed. I tried to do it using nested for loops, and I also tried it as two separate function, but neither attempt worked. I am now trying to get it done using one loop as below, but get this error

UnboundLocalError: local variable 'linel' referenced before assignment

Here is the code. I

F = 'file1.txt'
Fl = 'file2.txt'


 X = []               # Creats Data Lists
 M = []
 Id1 = []
 Id2 = []
 LC = 10
 N = 11

 fl = open(Fl)
 fl.readline()
 nlinesl = islice(fl,N)
 f = open(F)           #Opens file
 f.readline()          # Strips Header
 nlines = islice(f, N) #slices file to only read N lines


 for line in nlines and linel in nlinesl:             
    if line !='':
     linel = linel.strip()
     linel = linel.replace('\t','')
     columnsl = linel.split()
     lum = float(columnsl[1])
     if lum != LC:
      continue
     id1 = int(columnsl[0])
     Id1.append(id1)
     if line !='':
       line = line.strip()
       line = line.replace('\t','')
       columns = line.split()
       id2 = int(columns[1])
       Id2.append(id2)
       if Id !=  Id2:
        continue  
       x = columns[2]             # assigns variable to columns
       X.append(x)


  print(X)

here is an example of what I would like to happen
Two files

file1= 1 1 1 1     file2 =  1 1 1 1
       2 5 1 1              1 2 1 1
       2 3 4 4              1 1 1 1
Lc = 5
Xa = 1

So only the second line of file1 will survive, which means that only the second line in file2 will be processed because they have the same id. In my files the ids are

 id = columns[0] for file1 

and

 id = columns[1] for file2

Thanks in advance

Answer 1

I don’t think this is legal syntax:

 for line in nlines and linel in nlinesl:           

Try this instead:

 for line, line1 in zip(nlines, nlines1):

Also, these are tricky/easy to get wrong variable names 🙂

E.g.,

a = range(20, 26)
b = range(200, 226)

#for i in a and j in b:  # causes 
#   print i, j           # error

for i, j in zip(a, b):
   print i, j

generates output as expected

20 200
21 201
22 202
23 203
24 204
25 205