Cfrgtkky

segmented is a list of lists. Each element could be list of one or more string elements. And each string element is of the form:

Block1: some strings
Block2: some strings

Now not all string elements need to have Block2.
I want to run a loop where each element in 'segmented' is selected and then further loops with the secondary elements and tests for Block2. If present the string after Block2 is selected. IF there are more than 1 secondary elements then all the string is joined to a single string. The code I tried is as below

blk2 = re.compile(r'Block2:(.*)', re.DOTALL)

list1 = 

for i in segmented:

    secondlist = 

    for j in i:

      if re.search(blk2, j).group(1) is not None: # testing if Block2 exists

         txt = re.search(blk2, j).group(1) # picking up strings after Block2.

         secondlist.append(txt) #appending the string to an intermediate list

         'n'.join(secondlist) #if there are more than 1 element in secondlist joining them to one element

         list1.append(secondlist[0]) # appending the joined element to  list1

I keep getting NoneType errors. What am I doing wrong?

The source of your problem is row:

if re.search(blk2, j).group(1) is not None:

This code fails when j contains only Block1 (no Block2).
In such case search does not match anything, so the result of search
is None.

Then, on None object (of type NoneType), you attempt to call group(1)
which raises exception AttributeError: 'NoneType' object has no attribute 'group'.

Another remark: There is no need to call search twice, as you did.

So change this fragment to:

m = re.search(blk2, j)

if m:

    txt = m.group(1)

Additional hints:

1. Change the regex to r'Block2:s*(.*)' (I added s*).
   This way you avoid keeping initial space(s) from each Block2, if any.




2. It is not clear, why you use secondlist.
   Maybe you should add the strings matched directly to list1.