Parsing GenBank to FASTA with yield in Python (x, y) - python

For now I have tried to define and document my own function to do it, but I am encountering issues with testing the code and I have actually no idea if it is correct. I found some solutions with BioPython, re or other, but I really want to make this work with yield.
#generator for GenBank to FASTA
def parse_GB_to_FASTA (lines):
#set Default label
curr_label = None
#set Default sequence
curr_seq = ""
for line in lines:
#if the line starts with ACCESSION this should be saved as the beginning of the label
if line.startswith('ACCESSION'):
#if the label has already been changed
if curr_label is not None:
#output the label and sequence
yield curr_label, curr_seq
''' if the label starts with ACCESSION, immediately replace the current label with
the next ACCESSION number and continue with the next check'''
#strip the first column and leave the number
curr_label = '>' + line.strip()[12:]
#check for the organism column
elif line.startswith (' ORGANISM'):
#add the organism name to the label line
curr_label = curr_label + " " + line.strip()[12:]
#check if the region of the sequence starts
elif line.startswith ('ORIGIN'):
#until the end of the sequence is reached
while line.startswith ('//') is False:
#get a line without spaces and numbers
curr_seq += line.upper().strip()[12:].translate(None, '1234567890 ')
#if no more lines, then give the last label and sequence
yield curr_label, curr_seq

I often work with very large GenBank files and found (years ago) that the BioPython parsers were too brittle to make it through 100's of thousands of records (at the time), without crashing on an unusual record.
I wrote a pure python(2) function to return the next whole record from an open file, reading in 1k chunks, and leaving the file pointer ready to get the next record. I tied this in with a simple iterator that uses this function, and a GenBank Record class which has a fasta(self) method to get a fasta version.
YMMV, but the function that gets the next record is here as should be pluggable in any iterator scheme you want to use. As far as converting to fasta goes you can use logic similar to your ACCESSION and ORIGIN grabbing above, or you can get the text of sections (like ORIGIN) using:
sectionTitle='ORIGIN'
searchRslt=re.search(r'^(%s.+?)^\S'%sectionTitle,
gbrText,re.MULTILINE | re.DOTALL)
sectionText=searchRslt.groups()[0]
Subsections like ORGANISM, require a left side pad of 5 spaces.
Here's my solution to the main issue:
def getNextRecordFromOpenFile(fHandle):
"""Look in file for the next GenBank record
return text of the record
"""
cSize =1024
recFound = False
recChunks = []
try:
fHandle.seek(-1,1)
except IOError:
pass
sPos = fHandle.tell()
gbr=None
while True:
cPos=fHandle.tell()
c=fHandle.read(cSize)
if c=='':
return None
if not recFound:
locusPos=c.find('\nLOCUS')
if sPos==0 and c.startswith('LOCUS'):
locusPos=0
elif locusPos == -1:
continue
if locusPos>0:
locusPos+=1
c=c[locusPos:]
recFound=True
else:
locusPos=0
if (len(recChunks)>0 and
((c.startswith('//\n') and recChunks[-1].endswith('\n'))
or (c.startswith('\n') and recChunks[-1].endswith('\n//'))
or (c.startswith('/\n') and recChunks[-1].endswith('\n/'))
)):
eorPos=0
else:
eorPos=c.find('\n//\n',locusPos)
if eorPos == -1:
recChunks.append(c)
else:
recChunks.append(c[:(eorPos+4)])
gbrText=''.join(recChunks)
fHandle.seek(cPos-locusPos+eorPos)
return gbrText

Related

My code is missing some of the lines im trying to get out of a file

The basic task is to write a function, get_words_from_file(filename), that returns a list of lower case words that are within the region of interest. They share with you a regular expression: "[a-z]+[-'][a-z]+|[a-z]+[']?|[a-z]+", that finds all words that meet this definition. My code works well on some of the tests but fails when the line that indicates the region of interest is repeated.
Here's is my code:
import re
def get_words_from_file(filename):
"""Returns a list of lower case words that are with the region of
interest, every word in the text file, but, not any of the punctuation."""
with open(filename,'r', encoding='utf-8') as file:
flag = False
words = []
count = 0
for line in file:
if line.startswith("*** START OF"):
while count < 1:
flag=True
count += 1
elif line.startswith("*** END"):
flag=False
break
elif(flag):
new_line = line.lower()
words_on_line = re.findall("[a-z]+[-'][a-z]+|[a-z]+[']?|[a-z]+",
new_line)
words.extend(words_on_line)
return words
#test code:
filename = "bee.txt"
words = get_words_from_file(filename)
print(filename, "loaded ok.")
print("{} valid words found.".format(len(words)))
print("Valid word list:")
for word in words:
print(word)
The issue is the string "*** START OF" is repeated and isn't included when it is inside the region of interest.
The test code should result in:
bee.txt loaded ok.↩
16 valid words found.↩
Valid word list:↩
yes↩
really↩
this↩
time↩
start↩
of↩
synthetic↩
test↩
case↩
end↩
synthetic↩
test↩
case↩
i'm↩
in↩
too
But I'm getting:
bee.txt loaded ok.↩
11 valid words found.↩
Valid word list:↩
yes↩
really↩
this↩
time↩
end↩
synthetic↩
test↩
case↩
i'm↩
in↩
too
Any help would be great!
Attached is a screenshot of the file
The specific problem of your code is the if .. elif .. elif statement, you're ignoring all lines that look like the line that signals the start or end of a block, even if it's in the test block.
You wanted something like this for your function:
def get_words_from_file(filename):
"""Returns a list of lower case words that are with the region of
interest, every word in the text file, but, not any of the punctuation."""
with open(filename, 'r', encoding='utf-8') as file:
in_block = False
words = []
for line in file:
if not in_block and line == "*** START OF A SYNTHETIC TEST CASE ***\n":
in_block = True
elif in_block and line == "*** END TEST CASE ***\n":
break
elif in_block:
words_on_line = re.findall("[a-z]+[-'][a-z]+|[a-z]+[']?|[a-z]+", line.lower())
words.extend(words_on_line)
return words
This is assuming you are actually looking for the whole line as a marker, but of course you can still use .startswith() if you actually accept that as the start or end of the block, as long as it's sufficiently unambiguous.
Your idea of using a flag is fine, although naming a flag to whatever it represents is always a good idea.

Problem skipping line whilst iterating using previous line and current line comparison

I have a list of sorted data arranged so that each item in the list is a csv line to be written to file.
The final step of the script checks the contents of each field and if all but the last field match then it will copy the current line's last field onto the previous line's last field.
I would like to as I've found and processed one of these matches skip the current line where the field was copied from thus only leaving one of the lines.
Here's an example set of data
field1,field2,field3,field4,something
field1,field2,field3,field4,else
Desired output
field1,field2,field3,field4,something else
This is what I have so far
output_csv = ['field1,field2,field3,field4,something',
'field1,field2,field3,field4,else']
# run through the output
# open and create a csv file to save output
with open('output_table.csv', 'w') as f:
previous_line = None
part_duplicate_line = None
part_duplicate_flag = False
for line in output_csv:
part_duplicate_flag = False
if previous_line is not None:
previous = previous_line.split(',')
current = line.split(',')
if (previous[0] == current[0]
and previous[1] == current[1]
and previous[2] == current[2]
and previous[3] == current[3]):
print(previous[0], current[0])
previous[4] = previous[4].replace('\n', '') + ' ' + current[4]
part_duplicate_line = ','.join(previous)
part_duplicate_flag = True
f.write(part_duplicate_line)
if part_duplicate_flag is False:
f.write(previous_line)
previous_line = line
ATM script adds the line but doesn't skip the next line, I've tried various renditions of continue statements after part_duplicate_line is written to file but to no avail.
Looks like you want one entry for each combination of the first 4 fields
You can use a dict to aggregate data -
#First we extract the key and values
output_csv_keys = list(map(lambda x: ','.join(x.split(',')[:-1]), output_csv))
output_csv_values = list(map(lambda x: x.split(',')[-1], output_csv))
#Then we construct a dictionary with these keys and combine the values into a list
from collections import defaultdict
output_csv_dict = defaultdict(list)
for key, value in zip(output_csv_keys, output_csv_values):
output_csv_dict[key].append(value)
#Then we extract the key/value combinations from this dictionary into a list
for_printing = [','.join([k, ' '.join(v)]) for k, v in output_csv_dict.items()]
print(for_printing)
#Output is ['field1,field2,field3,field4,something else']
#Each entry of this list can be output to the csv file
I propose to encapsulate what you want to do in a function where the important part obeys this logic:
either join the new info to the old record
or output the old record and forget it
of course at the end of the loop we have in any case a dangling old record to output
def join(inp_fname, out_fname):
'''Input file contains sorted records, when two (or more) records differ
only in the last field, we join the last fields with a space
and output only once, otherwise output the record as-is.'''
######################### Prepare for action ##########################
from csv import reader, writer
with open(inp_fname) as finp, open(out_fname, 'w') as fout:
r, w = reader(finp), writer(fout)
######################### Important Part starts here ##############
old = next(r)
for new in r:
if old[:-1] == new[:-1]:
old[-1] += ' '+new[-1]
else:
w.writerow(old)
old = new
w.writerow(old)
To check what I've proposed you can use these two snippets (note that these records are shorter than yours, but it's an example and it doesn't matter because we use only -1 to index our records).
The 1st one has a "regular" last record
open('a0.csv', 'w').write('1,1,2\n1,1,3\n1,2,0\n1,3,1\n1,3,2\n3,3,0\n')
join('a0.csv', 'a1.csv')
while the 2nd has a last record that must be joined to the previous one.
open('b0.csv', 'w').write('1,1,2\n1,1,3\n1,2,0\n1,3,1\n1,3,2\n')
join('b0.csv', 'b1.csv')
If you run the snippets, as I have done before posting, in the environment where you have defined join you should get what you want.

Use Python xlsxwriter module to write srt data into and excel

this time I tried to use Python's xlsxwriter module to write data from a .srt into an excel.
The subtitle file looks like this in sublime text:
but I want to write the data into an excel, so it looks like this:
It's my first time to code python for this, so I'm still in the stage of trial and error...I tried to write some code like below
but I don't think it makes sense...
I'll continue trying out, but if you know how to do it, please let me know. I'll read your code and try to understand them! Thank you! :)
The following breaks the problem into a few pieces:
Parsing the input file. parse_subtitles is a generator that takes a source of lines and yields up a sequence of records in the form {'index':'N', 'timestamp':'NN:NN:NN,NNN -> NN:NN:NN,NNN', 'subtitle':'TEXT'}'. The approach I took was to track which of three distinct states we're in:
seeking to next entry for when we're looking for the next index number, which should match the regular expression ^\d*$ (nothing but a bunch of numbers)
looking for timestamp when an index is found and we expect a timestamp to come in the next line, which should match the regular expression ^\d{2}:\d{2}:\d{2},\d{3} --> \d{2}:\d{2}:\d{2},\d{3}$ (HH:MM:SS,mmm -> HH:MM:SS,mmm) and
reading subtitles while consuming actual subtitle text, with blank lines and EOF interpreted as subtitle termination points.
Writing the above records to a row in a worksheet. write_dict_to_worksheet accepts a row and worksheet, plus a record and a dictionary defining the Excel 0-indexed column numbers for each of the record's keys, and then it writes the data appropriately.
Organizaing the overall conversion convert accepts an input filename (e.g. 'Wildlife.srt' that'll be opened and passed to the parse_subtitles function, and an output filename (e.g. 'Subtitle.xlsx' that will be created using xlsxwriter. It then writes a header and, for each record parsed from the input file, writes that record to the XLSX file.
Logging statements left in for self-commenting purposes, and because when reproducing your input file I fat-fingered a : to a ; in a timestamp, making it unrecognized, and having the error pop up was handy for debugging!
I've put a text version of your source file, along with the below code, in this Gist
import xlsxwriter
import re
import logging
def parse_subtitles(lines):
line_index = re.compile('^\d*$')
line_timestamp = re.compile('^\d{2}:\d{2}:\d{2},\d{3} --> \d{2}:\d{2}:\d{2},\d{3}$')
line_seperator = re.compile('^\s*$')
current_record = {'index':None, 'timestamp':None, 'subtitles':[]}
state = 'seeking to next entry'
for line in lines:
line = line.strip('\n')
if state == 'seeking to next entry':
if line_index.match(line):
logging.debug('Found index: {i}'.format(i=line))
current_record['index'] = line
state = 'looking for timestamp'
else:
logging.error('HUH: Expected to find an index, but instead found: [{d}]'.format(d=line))
elif state == 'looking for timestamp':
if line_timestamp.match(line):
logging.debug('Found timestamp: {t}'.format(t=line))
current_record['timestamp'] = line
state = 'reading subtitles'
else:
logging.error('HUH: Expected to find a timestamp, but instead found: [{d}]'.format(d=line))
elif state == 'reading subtitles':
if line_seperator.match(line):
logging.info('Blank line reached, yielding record: {r}'.format(r=current_record))
yield current_record
state = 'seeking to next entry'
current_record = {'index':None, 'timestamp':None, 'subtitles':[]}
else:
logging.debug('Appending to subtitle: {s}'.format(s=line))
current_record['subtitles'].append(line)
else:
logging.error('HUH: Fell into an unknown state: `{s}`'.format(s=state))
if state == 'reading subtitles':
# We must have finished the file without encountering a blank line. Dump the last record
yield current_record
def write_dict_to_worksheet(columns_for_keys, keyed_data, worksheet, row):
"""
Write a subtitle-record to a worksheet.
Return the row number after those that were written (since this may write multiple rows)
"""
current_row = row
#First, horizontally write the entry and timecode
for (colname, colindex) in columns_for_keys.items():
if colname != 'subtitles':
worksheet.write(current_row, colindex, keyed_data[colname])
#Next, vertically write the subtitle data
subtitle_column = columns_for_keys['subtitles']
for morelines in keyed_data['subtitles']:
worksheet.write(current_row, subtitle_column, morelines)
current_row+=1
return current_row
def convert(input_filename, output_filename):
workbook = xlsxwriter.Workbook(output_filename)
worksheet = workbook.add_worksheet('subtitles')
columns = {'index':0, 'timestamp':1, 'subtitles':2}
next_available_row = 0
records_processed = 0
headings = {'index':"Entries", 'timestamp':"Timecodes", 'subtitles':["Subtitles"]}
next_available_row=write_dict_to_worksheet(columns, headings, worksheet, next_available_row)
with open(input_filename) as textfile:
for record in parse_subtitles(textfile):
next_available_row = write_dict_to_worksheet(columns, record, worksheet, next_available_row)
records_processed += 1
print('Done converting {inp} to {outp}. {n} subtitle entries found. {m} rows written'.format(inp=input_filename, outp=output_filename, n=records_processed, m=next_available_row))
workbook.close()
convert(input_filename='Wildlife.srt', output_filename='Subtitle.xlsx')
Edit: Updated to split multiline subtitles across multiple rows in output

Python Find Method in Strings Seems To Be Failing

I have a text file like so: http://pastie.org/10309944
This contains numbers corresponding to lists of EDI segments that could possibly be associated with them. My goal is to write a script that takes in one of these codes (the numbers) as input and outputs the corresponding lists. The lists are surrounded by "-" characters to make the parsing easier.
I wrote the following code: `class SegmentsUsedFinder(object):
'''Finds a transaction code and returns the possible segments used.
'''
def __init__(self, transaction_code):
'''Initializes the segment finder.
Args:
transaction_code: The transaction code to find possible segments from.
'''
self._transaction_code = transaction_code + " -"
def find_segment(self):
'''Finds the possible segments that correspond to the
transaction code.
'''
fileObject = open("transactioncodes.txt", 'r')
data = ""
for line in fileObject:
line = line.rstrip('\n').rstrip()
data += line
fileObject.close()
position = data.find(self._transaction_code) + len(self._transaction_code)
with open("transactioncodes.txt", 'r') as file:
file.seek(position)
segments = ""
char = ""
while True:
char = file.read(1)
if char == "-":
break
segments += char
return segments
I then create a finder object like so:
finder = SegmentsUsedFinder("270")
print finder.find_segment()
This code actually works but when I adjust the string inside the SegmentsUsedFinder constructor to 271 or 837 it fails for some reason. I think I'm perhaps misusing the find method, but it works for the first instance. I can also get it to work for 271 if I add 2 to position and to work for 837 if I add 4 to position.
Any help would be greatly appreciated, thanks.
Here's how your find_segment method should look like:
def find_segment(self):
'''Finds the possible segments that correspond to the
transaction code.
'''
with open("transactioncodes.txt", 'r') as _file:
for line in _file:
if line.startswith(self._transaction_code):
return line[len(self._transaction_code):line.rfind("-")]
return ""
Of course it can be improved (the file name to be a private member of the class), but this is a prototype that works (assuming that all the lines respect the pattern: ID -LIST-).
Note: I also renamed the variable name to _file because it was shadowing the builtin file type.

Python - reading data from file with variable attributes and line lengths

I'm trying to find the best way to parse through a file in Python and create a list of namedtuples, with each tuple representing a single data entity and its attributes. The data looks something like this:
UI: T020
STY: Acquired Abnormality
ABR: acab
STN: A1.2.2.2
DEF: An abnormal structure, or one that is abnormal in size or location, found
in or deriving from a previously normal structure. Acquired abnormalities are
distinguished from diseases even though they may result in pathological
functioning (e.g., "hernias incarcerate").
HL: {isa} Anatomical Abnormality
UI: T145
RL: exhibits
ABR: EX
RIN: exhibited_by
RTN: R3.3.2
DEF: Shows or demonstrates.
HL: {isa} performs
STL: [Animal|Behavior]; [Group|Behavior]
UI: etc...
While several attributes are shared (eg UI), some are not (eg STY). However, I could hardcode an exhaustive list of necessary.
Since each grouping is separated by an empty line, I used split so I can process each chunk of data individually:
input = file.read().split("\n\n")
for chunk in input:
process(chunk)
I've seen some approaches use string find/splice, itertools.groupby, and even regexes. I was thinking of doing a regex of '[A-Z]*:' to find where the headers are, but I'm not sure how to approach pulling out multiple lines afterwards until another header is reached (such as the multilined data following DEF in the first example entity).
I appreciate any suggestions.
I took assumption that if you have string span on multiple lines you want newlines replaced with spaces (and to remove any additional spaces).
def process_file(filename):
reg = re.compile(r'([\w]{2,3}):\s') # Matches line header
tmp = '' # Stored/cached data for mutliline string
key = None # Current key
data = {}
with open(filename,'r') as f:
for row in f:
row = row.rstrip()
match = reg.match(row)
# Matches header or is end, put string to list:
if (match or not row) and key:
data[key] = tmp
key = None
tmp = ''
# Empty row, next dataset
if not row:
# Prevent empty returns
if data:
yield data
data = {}
continue
# We do have header
if match:
key = str(match.group(1))
tmp = row[len(match.group(0)):]
continue
# No header, just append string -> here goes assumption that you want to
# remove newlines, trailing spaces and replace them with one single space
tmp += ' ' + row
# Missed row?
if key:
data[key] = tmp
# Missed group?
if data:
yield data
This generator returns dict with pairs like UI: T020 in each iteration (and always at least one item).
Since it uses generator and continuous reading it should be effective event on large files and it won't read whole file into memory at once.
Here's little demo:
for data in process_file('data.txt'):
print('-'*20)
for i in data:
print('%s:'%(i), data[i])
print()
And actual output:
--------------------
STN: A1.2.2.2
DEF: An abnormal structure, or one that is abnormal in size or location, found in or deriving from a previously normal structure. Acquired abnormalities are distinguished from diseases even though they may result in pathological functioning (e.g., "hernias incarcerate").
STY: Acquired Abnormality
HL: {isa} Anatomical Abnormality
UI: T020
ABR: acab
--------------------
DEF: Shows or demonstrates.
STL: [Animal|Behavior]; [Group|Behavior]
RL: exhibits
HL: {isa} performs
RTN: R3.3.2
UI: T145
RIN: exhibited_by
ABR: EX
source = """
UI: T020
STY: Acquired Abnormality
ABR: acab
STN: A1.2.2.2
DEF: An abnormal structure, or one that is abnormal in size or location, found
in or deriving from a previously normal structure. Acquired abnormalities are
distinguished from diseases even though they may result in pathological
functioning (e.g., "hernias incarcerate").
HL: {isa} Anatomical Abnormality
"""
inpt = source.split("\n") #just emulating file
import re
reg = re.compile(r"^([A-Z]{2,3}):(.*)$")
output = dict()
current_key = None
current = ""
for line in inpt:
line_match = reg.match(line) #check if we hit the CODE: Content line
if line_match is not None:
if current_key is not None:
output[current_key] = current #if so - update the current_key with contents
current_key = line_match.group(1)
current = line_match.group(2)
else:
current = current + line #if it's not - it should be the continuation of previous key line
output[current_key] = current #don't forget the last guy
print(output)
import re
from collections import namedtuple
def process(chunk):
split_chunk = re.split(r'^([A-Z]{2,3}):', chunk, flags=re.MULTILINE)
d = dict()
fields = list()
for i in xrange(len(split_chunk)/2):
fields.append(split_chunk[i])
d[split_chunk[i]] = split_chunk[i+1]
my_tuple = namedtuple(split_chunk[1], fields)
return my_tuple(**d)
should do. I think I'd just do the dict though -- why are you so attached to a namedtuple?

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