def GC_info(seq, win_len, step):
"""
Calculate needed %GC information.
Calculate G+C content, minimal %GC in sliding windows, maximal %GC in
sliding windows, stdev of %GC in sliding windows, and CV of %GC in sliding
windows
For GC content, it returns the percentage (float between 0 and 100).
Copes mixed case sequences, and with the ambiguous nucleotide S (G or C)
when counting the G and C content. The percentage is calculated against
the length of the sequence using A,C,G,T,S,W with Ns, e.g.:
>>> GC("ACTGN")
50.0
Note that this will return zero for an empty sequence.
"""
gc = GC(seq)
tmp_gc = []
if win_len >= len(seq):
return gc, gc, gc, 0, 0
for i in range(0, len(seq) - win_len):
tmp_gc.append(GC(seq[i:i + win_len]))
sd = numpy.std(tmp_gc)
# Applying +1 to GC to make sure we do not divide by 0
return gc, min(tmp_gc), max(tmp_gc), sd, 100. * sd / (gc + 1.)
def bg_len_GC_bins(bg, bg_dir):
"""
Get lengths info for background sequences.
Compute G+C content for all sequences in the background and store the
information in a list. To each G+C percentage bin, we associate the
corresponding sequence names with information about GC composition within
sliding windows.
Return info in lists.
"""
stream = open(bg)
gc_bins = []
gc_list = []
lengths = []
for _ in xrange(0, 101):
gc_bins.append({})
for record in SeqIO.parse(stream, "fasta"):
gc = GC(record.seq)
gc_list.append(gc)
if len(record) in gc_bins[gc]:
gc_bins[gc][len(record)].append(record)
else:
gc_bins[gc][len(record)] = [record]
lengths.append(len(record.seq))
stream.close()
print_in_bg_dir(gc_bins, bg_dir, True)
return gc_list, gc_bins, lengths
def fg_len_GC_bins(fg_file):
"""
Compute G+C content for all sequences in the foreground.
Computes %GC contant and store the information in a list. To each G+C
percentage bin, we associate the number of sequences falling in the
corresponding bin.
Return lists of GC contents, GC bins, and lengths distrib.
"""
stream = open(fg_file)
gc_bins = []
for _ in range(0, 101):
gc_bins.append({})
gc_list = []
lengths = []
for record in SeqIO.parse(stream, "fasta"):
gc = GC(record.seq)
gc_list.append(gc)
length = len(record)
lengths.append(length)
if length in gc_bins[gc]:
gc_bins[gc][length] += 1
else:
gc_bins[gc][length] = 1
stream.close()
return gc_list, gc_bins, lengths
def bg_len_GC_bins(bg_file, bg_dir):
"""
Compute G+C content for all sequences in the background.
Compute and store the %GC information in a list. To each G+C percentage
bin, we associate the corresponding sequence names.
Return lists of GC contents, GC bins, and lengths distrib.
"""
stream = open(bg_file)
gc_bins = []
gc_list = []
lengths = []
for _ in range(0, 101):
gc_bins.append({})
for record in SeqIO.parse(stream, "fasta"):
gc = GC(record.seq)
gc_list.append(gc)
if len(record) in gc_bins[gc]:
gc_bins[gc][len(record)].append(record)
else:
gc_bins[gc][len(record)] = [record]
lengths.append(len(record.seq))
stream.close()
print_in_bg_dir(gc_bins, bg_dir, True)
return gc_list, gc_bins, lengths
def fg_GC_bins(fg_file):
"""Computes G+C content for all sequences in the foreground and store the
information in a list. To each G+C percentage bin, we associate the number of
sequences falling in the corresponding bin
"""
stream = open(fg_file)
gc_bins = [0] * 101
gc_list = []
lengths = []
for record in SeqIO.parse(stream, "fasta"):
gc = GC(record.seq)
gc_list.append(gc)
gc_bins[gc] += 1
lengths.append(len(record.seq))
stream.close()
return gc_list, gc_bins, lengths
def generate_sequences(seqs, winlen, step, nfold):
"""
Shuffle sequences within a sliding window, keeping mononuc compo.
Return %GC and length distribution of output sequences.
"""
bg_gc_list = []
bg_lengths = []
for record in seqs:
sequence = record.seq.__str__()
for _ in range(0, nfold):
new_sequence = shuffle_window(sequence, winlen, step)
new_seq = SeqRecord(Seq(new_sequence, generic_dna),
id="background_seq_{}".format(record.name),
description="")
print(new_seq.format("fasta"), end="")
bg_gc_list.append(GC(new_sequence))
bg_lengths.append(len(new_sequence))
return bg_gc_list, bg_lengths
def bg_GC_bins(bg_file):
""" Computes G+C content for all sequences in the background and store the
information in a list. To each G+C percentage bin, we associate the
corresponding sequence names
"""
stream = open(bg_file)
gc_bins = []
gc_list = []
lengths = []
for i in range(0, 101):
gc_bins.append([])
for record in SeqIO.parse(stream, "fasta"):
gc = GC(record.seq)
gc_list.append(gc)
gc_bins[gc].append(record)
lengths.append(len(record.seq))
stream.close()
return gc_list, gc_bins, lengths
def generate_sequences(seqs, winlen, step, nfold):
bg_gc_list = []
bg_lengths = []
for record in seqs:
seq = record.seq.__str__()
for n in range(0, nfold):
new_sequence = ""
for sequence in split_seq(seq):
if re.match("N", sequence):
new_sequence += sequence
elif sequence:
new_sequence += shuffle_window(sequence, winlen, step)
new_seq = SeqRecord(Seq(new_sequence, generic_dna),
id="background_seq_for_{}".format(record.name),
description="")
print(new_seq.format("fasta"), end="")
bg_gc_list.append(GC(new_sequence))
bg_lengths.append(len(new_sequence))
return bg_gc_list, bg_lengths
def generate_sequences(seqs, nfold):
"""
Generate sequences by shuffling input (mononucleotide).
return tuple containing %GC compo and length distrib of output.
"""
bg_gc_list = []
bg_lengths = []
for record in seqs:
seq = record.seq.__str__()
for _ in range(0, nfold):
new_sequence = "".join(random.sample(seq, len(seq)))
new_seq = SeqRecord(Seq(new_sequence, generic_dna),
id="background_seq_for_{}".format(record.name),
description="")
print(new_seq.format("fasta"), end="")
bg_gc_list.append(GC(new_sequence))
bg_lengths.append(len(new_sequence))
return bg_gc_list, bg_lengths
def bg_GC_bins(bg_file, bg_dir):
"""
Compute G+C content for all sequences in the background.
Compute and store the GC information in a list. To each G+C percentage bin,
we associate the corresponding sequence names.
Files representing the binning are stored in the "bg_dir" directory.
Return lists of GC contents, GC bins, and lengths distrib.
"""
stream = open(bg_file)
gc_bins = []
gc_list = []
lengths = []
for _ in xrange(0, 101):
gc_bins.append([])
for record in SeqIO.parse(stream, "fasta"):
gc = GC(record.seq)
gc_list.append(gc)
gc_bins[gc].append(record)
lengths.append(len(record.seq))
stream.close()
print_in_bg_dir(gc_bins, bg_dir)
return gc_list, gc_bins, lengths
wins = windows.slidingWindow(sequence,
size=windowSize,
step=overlap,
fillvalue="-")
# let's count the windows
i = 0
for window in wins:
if i % 100 == 0:
print("[STATUS] \t" + str(i) + " windows processed for " +
str(header) + ".",
end="\r")
# get the sequence
seq = ''.join(window)
# calculate GC stats
currentWindow = str(bin_int) + '-' + str(bin_int + windowSize)
PerGC, GCSkew, nucleotideCounts = GC.GCStats(seq)
# calculate kmer stats
UniqueKmers = kmers.getUniqueKmers(seq, kmerLength)
formattedHeader = header.replace(">.", "")
GCperWindowCSV.write(formattedHeader + ',' + currentWindow + ',' +
str(PerGC) + ',' + str(GCSkew) + ',' +
str(UniqueKmers) + '\n')
# keep running total of nucleotide counts
totalNucleotideCounts = dictionaries.mergeDictionaries(
totalNucleotideCounts, nucleotideCounts)
if bin_int < seq_length - overlap:
bin_int += overlap
else:
bin_int = 0
