I am viewing the Python tutorials from the Pascal institute BDFL says are the best to start and i have a very basic question
While in the tutorial says:
How many of each base does this sequence contains?
>>> count(seq, 'a')
35
>>> count(seq, 'c')
21
>>> count(seq, 'g')
44
>>> count(seq, 't')
12
When i try to do is it does not work
>>> count(seq, 'a')
Traceback (most recent call last):
File "<pyshell#140>", line 1, in <module>
count(seq, 'a')
NameError: name 'count' is not defined
Why this is happening?
I' ve searched Stack resoures BTW and I didn't find anything.
COMMENT
Take a look at the start of the section 1.1.3. You have to type first from string import *
>>> from string import*
>>> nb_a = count(seq, 'a')
Traceback (most recent call last):
File "<pyshell#73>", line 1, in <module>
nb_a = count(seq, 'a')
NameError: name 'count' is not defined
>>> from string import *
>>> nb_a = count(seq, 'a')
Traceback (most recent call last):
File "<pyshell#75>", line 1, in <module>
nb_a = count(seq, 'a')
NameError: name 'count' is not defined
I did.
ANSWER
>>> from string import *
>>> from string import count
Traceback (most recent call last):
File "<pyshell#93>", line 1, in <module>
from string import count
ImportError: cannot import name count
>>> from string import count
Traceback (most recent call last):
File "<pyshell#94>", line 1, in <module>
from string import count
ImportError: cannot import name count
I did. Didn' t work.
The tutorial you linked to is very old:
Python 2.4.2 (#1, Dec 20 2005, 16:25:40)
You're probably using a more modern Python (>= 3) in which case there are no longer string functions like count in the string module. We used to have
Python 2.7.5+ (default, Feb 27 2014, 19:39:55)
[GCC 4.8.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> from string import count
>>> count("abcc", "c")
2
but today:
Python 3.3.2+ (default, Feb 28 2014, 00:53:38)
[GCC 4.8.1] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from string import count
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ImportError: cannot import name count
>>> import string
>>> dir(string)
['ChainMap', 'Formatter', 'Template', '_TemplateMetaclass', '__builtins__',
'__cached__', '__doc__', '__file__', '__initializing__', '__loader__', '__name__',
'__package__', '_re', '_string', 'ascii_letters', 'ascii_lowercase',
'ascii_uppercase', 'capwords', 'digits', 'hexdigits', 'octdigits', 'printable',
'punctuation', 'whitespace']
These days we use the string methods instead, the ones that live in str itself:
>>> 'abcc'.count('c')
2
or even
>>> str.count('abcc','c')
2
While the other answers are correct, current Python releases propose another way to call count, as it is usable for str but also any type of sequence, as advised inside the documentation:
>>> seq.count('a')
35
As seq is as string object, it also have the count method.
This methodcount() is defined in string package. For using this method in your code, you need to import the definition.
Adding the following import statement before using the method will solve your problem
from string import count
>>> seq='acdaacc'
>>> count(seq,'a')
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'count' is not defined
>>> from string import count
>>> count(seq,'a')
3
count is a method in the string module, meaning that at the top of your file (before you use the function) you need to "import" it so that your interpreter knows what you're talking about. Add the line from string import count as the first line of your file and it should work.
Related
I have a strange problem I don't get. I have a format string with a lot of fields. I want to supply the content for the fields using a list. The following simple demo below shows the issue:
>>> formatstr = "Hello {}, you are my {} fried since {}"
>>> list = ["John", "best", 2020]
>>> print formatstr.format(list)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: tuple index out of range
>>>
The format string has 3 fields and the list has also 3 elements.
So I don't understand the error message.
Even when I try to address the indexes within the format string:
>>>
>>> formatstr = "Hello {0:}, you are my {1:} fried since {2:}"
>>>
>>> print formatstr.format(list)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
IndexError: tuple index out of range
>>>
Can you please help me? I think I blocked somewhere in my thinking.
Thanks.
recently i understand the great advantage to use the list comprehension. I am working with several milion of points (x,y,z) stored in a special format *.las file. In python there are two way to work with this format:
Liblas module [http://www.liblas.org/tutorial/python.html][1] (in a C++/Python)
laspy module [http://laspy.readthedocs.org/en/latest/tut_part_1.html][2] (pure Python)
I had several problem with liblas and i wish to test laspy.
in liblas i can use list comprehension as:
from liblas import file as lasfile
f = lasfile.File(inFile,None,'r') # open LAS
points = [(p.x,p.y) for p in f] # read in list comprehension
in laspy i cannot figurate how do the same:
from laspy.file import File
f = file.File(inFile, mode='r')
f
<laspy.file.File object at 0x0000000013939080>
(f[0].X,f[0].Y)
(30839973, 696447860)
i tryed several combination as:
points = [(p.X,p.Y) for p in f]
but i get this message
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
AttributeError: Point instance has no attribute 'x'
I tryed in uppercase and NOT-uppercase because Python is case sensitive:
>>> [(p.x,p.y) for p in f]
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
AttributeError: Point instance has no attribute 'x'
>>> [(p.X,p.Y) for p in f]
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
AttributeError: Point instance has no attribute 'X'
this is in interactive prompt:
C:\Python27>python.exe
Python 2.7.3 (default, Apr 10 2012, 23:24:47) [MSC v.1500 64 bit (AMD64)] on win
32
Type "help", "copyright", "credits" or "license" for more information.
>>> from laspy.file import File
>>> inFile="C:\\04-las_clip_inside_area\\Ku_018_class.las"
>>> f = File(inFile, None, 'r')
>>> f
<laspy.file.File object at 0x00000000024D5E10>
>>> points = [(p.X,p.Y) for p in f]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: Point instance has no attribute 'X'
>>>
the print p after the list is:
print dir(p)
['__doc__', '__init__', '__module__', 'make_nice', 'pack', 'packer', 'reader', 'unpacked']
in a loop format i have always the same error
>>> for p in f:
... print dir(p)
... print p.X,p.Y
...
['__doc__', '__init__', '__module__', 'make_nice', 'pack', 'packer', 'reader', 'unpacked']
Traceback (most recent call last):
File "<interactive input>", line 3, in <module>
AttributeError: Point instance has no attribute 'X'
using this code suggested by nneonneo
import numpy as np
for p in f:
... points = np.array([f.X, f.Y]).T
i can store in an array
points
array([[ 30839973, 696447860],
[ 30839937, 696447890],
[ 30839842, 696447832],
...,
[ 30943795, 695999984],
[ 30943695, 695999922],
[ 30943960, 695999995]])
but miss the way to create a list comprehension
points = [np.array(p.X,p.Y).T for p in f]
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
AttributeError: Point instance has no attribute 'X'
thanks in advance for help.
Gianni
Python is case-sensitive. Too me it looks like you ask for attribute x, but it should be an uppercase X.
Try
import numpy as np
...
points = np.array([f.X, f.Y]).T
It looks like Point has a make_nice() method that makes more attributes show up.
for p in f: p.make_nice()
Now your list comp should work (with uppercase X and Y--see comments below).
[(p.X,p.Y) for p in f]
note: This answer is not tested. It is based on reading the source of laspy.util.Point.
Relevant source:
def make_nice(self):
'''Turn a point instance with the bare essentials (an unpacked list of data)
into a fully populated point. Add all the named attributes it possesses,
including binary fields.
'''
i = 0
for dim in self.reader.point_format.specs:
self.__dict__[dim.name] = self.unpacked[i]
i += 1
# rest of method snipped
I have the following list:
>>> poly
'C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa.shp'
>>> record
1373155
and I wish to create:
'C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa_1373155.txt'
I wish to split in order to get the part "C:\04-las_clip_inside_area\16x16grids_1pp_fsa16x16grids_1pp_fsa".
I have tried this two-code-lines solution:
mylist = [poly.split(".")[0], "_", record, ".txt"]
>>> mylist
['C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa', '_', 1373155, '.txt']
from here, reading the example in Python join, why is it string.join(list) instead of list.join(string)?.
I find this solution to joint, but I get this error message:
>>> mylist.join("")
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
AttributeError: 'list' object has no attribute 'join'
Also if I use:
>>> "".join(mylist)
Traceback (most recent call last):
File "<interactive input>", line 1, in <module>
TypeError: sequence item 2: expected string, int found
Python join: why is it string.join(list) instead of list.join(string)?
So there is
"".join(mylist)
instead of
mylist.join("")
There's your error.
To solve your int/string problem, convert the int to string:
mylist= [poly.split(".")[0],"_",str(record),".txt"]
or write directly:
"{}_{}.txt".format(poly.split(".")[0], record)
>>> from os import path
>>>
>>> path.splitext(poly)
('C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa', '.shp')
>>>
>>> filename, ext = path.splitext(poly)
>>> "{0}_{1}.txt".format(filename, record)
'C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa_1373155.txt'
>>> poly = 'C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa.shp'
>>> record = 1373155
>>> "{}_{}.txt".format(poly.rpartition('.')[0], record)
'C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa_1373155.txt'
or if you insist on using join()
>>> "".join([poly.rpartition('.')[0], "_", str(record), ".txt"])
'C:\\04-las_clip_inside_area\\16x16grids_1pp_fsa_1373155.txt'
It's important to use rpartition() (or rsplit()) as otherwise it won't work properly if the path has any other '.''s in it
You need to convert record into a string.
mylist= [poly.split(".")[0],"_",str(record),".txt"]
I have a byte array containing data that is compressed by gzip.
Now I need to uncompress this data. How can this be achieved?
zlib.decompress(data, 15 + 32) should autodetect whether you have gzip data or zlib data.
zlib.decompress(data, 15 + 16) should work if gzip and barf if zlib.
Here it is with Python 2.7.1, creating a little gz file, reading it back, and decompressing it:
>>> import gzip, zlib
>>> f = gzip.open('foo.gz', 'wb')
>>> f.write(b"hello world")
11
>>> f.close()
>>> c = open('foo.gz', 'rb').read()
>>> c
'\x1f\x8b\x08\x08\x14\xf4\xdcM\x02\xfffoo\x00\xcbH\xcd\xc9\xc9W(\xcf/\xcaI\x01\x00\x85\x11J\r\x0b\x00\x00\x00'
>>> ba = bytearray(c)
>>> ba
bytearray(b'\x1f\x8b\x08\x08\x14\xf4\xdcM\x02\xfffoo\x00\xcbH\xcd\xc9\xc9W(\xcf/\xcaI\x01\x00\x85\x11J\r\x0b\x00\x00\x00')
>>> zlib.decompress(ba, 15+32)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: must be string or read-only buffer, not bytearray
>>> zlib.decompress(bytes(ba), 15+32)
'hello world'
>>>
Python 3.x usage would be very similar.
Update based on comment that you are running Python 2.2.1.
Sigh. That's not even the last release of Python 2.2. Anyway, continuing with the foo.gz file created as above:
Python 2.2.3 (#42, May 30 2003, 18:12:08) [MSC 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> strobj = open('foo.gz', 'rb').read()
>>> strobj
'\x1f\x8b\x08\x08\x14\xf4\xdcM\x02\xfffoo\x00\xcbH\xcd\xc9\xc9W(\xcf/\xcaI\x01\x00\x85\x11J\r\x0b\x00\x00\x00'
>>> import zlib
>>> zlib.decompress(strobj, 15+32)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
zlib.error: Error -2 while preparing to decompress data
>>> zlib.decompress(strobj, 15+16)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
zlib.error: Error -2 while preparing to decompress data
# OK, we can't use the back door method. Plan B: use the
# documented approach i.e. gzip.GzipFile with a file-like object.
>>> import gzip, cStringIO
>>> fileobj = cStringIO.StringIO(strobj)
>>> gzf = gzip.GzipFile('dummy-name', 'rb', 9, fileobj)
>>> gzf.read()
'hello world'
# Success. Now let's assume you have an array.array object-- which requires
# premeditation; they aren't created accidentally!
# The following code assumes subtype 'B' but should work for any subtype.
>>> import array, sys
>>> aaB = array.array('B')
>>> aaB.fromfile(open('foo.gz', 'rb'), sys.maxint)
Traceback (most recent call last):
File "<stdin>", line 1, in ?
EOFError: not enough items in file
#### Don't panic, just read the fine manual
>>> aaB
array('B', [31, 139, 8, 8, 20, 244, 220, 77, 2, 255, 102, 111, 111, 0, 203, 72, 205, 201, 201, 87, 40, 207, 47, 202, 73, 1, 0, 133, 17, 74, 13, 11, 0, 0, 0])
>>> strobj2 = aaB.tostring()
>>> strobj2 == strobj
1 #### means True
# You can make a str object and use that as above.
# ... or you can plug it directly into StringIO:
>>> gzip.GzipFile('dummy-name', 'rb', 9, cStringIO.StringIO(aaB)).read()
'hello world'
Apparently you can do this
import zlib
# ...
ungziped_str = zlib.decompressobj().decompress('x\x9c' + gziped_str)
Or this:
zlib.decompress( data ) # equivalent to gzdecompress()
For more info, look here: Python docs
I am trying to search and replace some of the text (eg 'Smith, John') in this pdf form file (header.fdf, I presumed this is treated as binary file):
'%FDF-1.2\n%\xe2\xe3\xcf\xd3\n1 0 obj\n<</FDF<</Fields[<</V(M)/T(PatientSexLabel)>><</V(24-09-1956 53)/T(PatientDateOfBirth)>><</V(Fisher)/T(PatientLastNameLabel)>><</V(CNSL)/T(PatientConsultant)>><</V(28-01-2010 18:13)/T(PatientAdmission)>><</V(134 Field Street\\rBlackburn BB1 1BB)/T(PatientAddressLabel)>><</V(Smith, John)/T(PatientName)>><</V(24-09-1956)/T(PatientDobLabel)>><</V(0123456)/T(PatientRxr)>><</V(01234567891011)/T(PatientNhsLabel)>><</V(John)/T(PatientFirstNameLabel)>><</V(0123456)/T(PatientRxrLabel)>>]>>>>\nendobj\ntrailer\n<</Root 1 0 R>>\n%%EOF\n'
After
f=open("header.fdf","rb")
s=f.read()
f.close()
s=s.replace(b'PatientName',name)
the following error occurs:
Traceback (most recent call last):
File "/home/aj/Inkscape/Med/GAD/gad.py", line 56, in <module>
s=s.replace(b'PatientName',name)
TypeError: expected an object with the buffer interface
How best to do this?
f=open("header.fdf","rb")
s=str(f.read())
f.close()
s=s.replace(b'PatientName',name)
or
f=open("header.fdf","rb")
s=f.read()
f.close()
s=s.replace(b'PatientName',bytes(name))
probably the latter, as I don't think you are going to be able to use unicode names with this type of substitution anyway
You must be using Python 3.X. You didn't define 'name' in your example, but it is the problem. Likely you defined it as a Unicode string:
name = 'blah'
It needs to be a bytes object too:
name = b'blah'
This works:
Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> f = open('file.txt','rb')
>>> s = f.read()
>>> f.close()
>>> s
b'Test File\r\n'
>>> name = b'Replacement'
>>> s=s.replace(b'File',name)
>>> s
b'Test Replacement\r\n'
In a bytes object, the arguments to replace must both be bytes objects.