recently, i am leaning biopython for job. However, I got some problem at first step I followed the biopython cookbook and their example did not work.

(python 3.4.2 and version 1.69)

according to cookbook

It contains 94 records, each has a line starting with “>” (greater-than symbol) followed by the sequence on one or more lines. Now try this in Python:

from Bio import SeqIO
for seq_record in SeqIO.parse("ls_orchid.fasta", "fasta"):
    printseq_record.id)
    print(repr(seq_record.seq))
    print(len(seq_record))

You shouldget something like this on your screen:

gi|2765658|emb|Z78533.1|CIZ78533
Seq('CGTAACAAGGTTTCCGTAGGTGAACCTGCGGAAGGATCATTGATGAGACCGTGG...CGC', SingleLetterAlphabet())
740

...
gi|2765564|emb|Z78439.1|PBZ78439
Seq('CATTGTTGAGATCACATAATAATTGATCGAGTTAATCTGGAGGATCTGTTTACT...GCC', SingleLetterAlphabet())
592

.

However, after i followed, I got this

from Bio import SeqIO
for seq_record in SeqIO.parse("ls_orchid.fasta", "fasta"):
    printseq_record.id)
    print(repr(seq_record.seq))
    print(len(seq_record))


Traceback (most recent call last):
  File "<pyshell#27>", line 1, in <module>
    for seq_record in SeqIO.parse("ls_orchid.fasta", "fasta"):
  File "C:\Python34\lib\site-packages\Bio\SeqIO\__init__.py", line 590, in parse
    with as_handle(handle, mode) as fp:
  File "C:\Python34\lib\contextlib.py", line 59, in __enter__
    return next(self.gen)
  File "C:\Python34\lib\site-packages\Bio\File.py", line 88, in as_handle
    with open(handleish, mode, **kwargs) as fp:
FileNotFoundError: [Errno 2] No such file or directory: 'ls_orchid.fasta'

Could anyone give some suggestions to solve this problem?

thanks a lot