Python 2 has two integer types: int, which is a signed integer whose size equals your machine's word size (but is always at least 32 bits), and long, which is unlimited in size.
Python 3 has only one integer type, which is called int but is equivalent to a Python 2 long.
Python 2 has two integer types: int, which is a signed integer whose size equals your machine's word size (but is always at least 32 bits), and long, which is unlimited in size.
Python 3 has only one integer type, which is called int but is equivalent to a Python 2 long.
You have a couple of options using gmpy. Here is one example using gmpy:
>>> from gmpy import mpz
>>> a=mpz(7)
>>> bin(a)
'0b111'
>>> a=a.setbit(48)
>>> bin(a)
'0b1000000000000000000000000000000000000000000000111'
>>>
gmpy2 is the development version of gmpy and includes a new type called xmpz that allows more direct access to the bits.
>>> from gmpy2 import xmpz
>>> a=xmpz(7)
>>> bin(a)
'0b111'
>>> a[48]=1
>>> bin(a)
'0b1000000000000000000000000000000000000000000000111'
>>>
There are other solutions such as bitarray you might want to look at.
Disclaimer: I maintain gmpy and gmpy2.
How can I use 64-bit integer in Python 3? - Stack Overflow
How best to store millions of pairs of 64 bit integers to save space?
Is there any way to force Python to use 64 bit integers on Windows? - Stack Overflow
Use 64-bit integers for bit counts
You've misinterpreted their warning. They're telling you to use a larger type than normal in order to avoid overflow issues seen with a 32-bit type. Since Python's int is essentially boundless there will never be an overflow issue.
Frankly, sometimes it is bad to use unlimited integers in Python. Best alternative is to use NumPy fixed length types if you really need exactly 32bit or 64bit ops.
import numpy as np
v = np.uint64(99)
q = np.uint64(12) * v + np.uint64(77)
print(q)
print(type(q))
You've misinterpreted their warning. They're telling you to use a larger type than normal in order to avoid overflow issues seen with a 32-bit type. Since Python's int is essentially boundless there will never be an overflow issue.
Frankly, sometimes it is bad to use unlimited integers in Python. Best alternative is to use NumPy fixed length types if you really need exactly 32bit or 64bit ops.
import numpy as np
v = np.uint64(99)
q = np.uint64(12) * v + np.uint64(77)
print(q)
print(type(q))
I have millions of pairs of 64 bit integers I want to put into a set. Speed and space are important to me.
I could put tuples of python ints into the set but python ints use a lot more than 64 bits each. numpy has the type uint64 but I can’t add numpy arrays to a set afaik.
I will be performing a lot of set add, query and remove operations which I need to be fast.
my_array = numpy.array(my_list,dtype=numpy.int64)
maybe?
I'm not aware of any Windows build that uses a 64-bit native type for int with Python 2.7. All C compilers will use long to refer to a 32 bit type. Changing Python to use long long for the internal representation of int would likely break extension modules.
On Python 3.x, the only integer type is the arbitrary precision type (known as long under Python 2.x). On 64-bit systems, the arbitrary precision type works in chunks of 2^30 bits. On 32-bit systems, the arbitrary precision type works in chunks of 2^15 bits. The values 15 and 30 would be difficult to change.
For external libraries, I maintain the gmpy2 library. It provides access to the arbitrary precision GMP/MPIR library. The gmpy2.mpz integer type is usually more efficient once numbers reach ~128 bits in length. YMMV.
So this is my system's biggest integer it can work with
>>> import sys >>> print sys.maxint 9223372036854775807
But python can easily work out
>>> sys.maxint**2 85070591730234615847396907784232501249L
How is that possible?
int and long were "unified" a few versions back. Before that it was possible to overflow an int through math ops.
3.x has further advanced this by eliminating long altogether and only having int.
- Python 2:
sys.maxintcontains the maximum value a Python int can hold.- On a 64-bit Python 2.7, the size is 24 bytes. Check with
sys.getsizeof().
- On a 64-bit Python 2.7, the size is 24 bytes. Check with
- Python 3:
sys.maxsizecontains the maximum size in bytes a Python int can be.- This will be gigabytes in 32 bits, and exabytes in 64 bits.
- Such a large int would have a value similar to 8 to the power of
sys.maxsize.
This PEP should help.
Bottom line is that you really shouldn't have to worry about it in python versions > 2.4