How to change the default gcc compiler for python - python

I have installed gcc 4.9.2 in my computer (mac osx 10.10, 64 bit), while gcc version 4.2 is shown in Python environment. I don't know why this happened.
I encountered some issues when calling numpy.f2py function, I thought it may be related with the incompatible gcc compiler.
1.Python shell
▶ python
Python 3.5.5 | packaged by conda-forge | (default, Jul 23 2018, 23:45:11)
[GCC 4.2.1 Compatible Apple LLVM 6.1.0 (clang-602.0.53)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
2.In terminal
▶ gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-apple-darwin14.0.0/4.9.2/lto-wrapper
Target: x86_64-apple-darwin14.0.0
Configured with: ../gcc-4.9-20141029/configure --enable-languages=c++,fortran
Thread model: posix
gcc version 4.9.2 20141029 (prerelease) (GCC)
I thought this problem may be due to that the gcc compiler was installed after python. How to fix this issue, wish for your advice.

I believe that [GCC 4.2.1 Compatible Apple LLVM 6.1.0 (clang-602.0.53)] you get when you start the python interactive shell is the compiler that was used to compile the python interpreter, it has nothing to do with which compiler is used with f2py.

Related

How to prevent terminal from picking up old python version 2.7.16 after installing 3.8

I have followed all the possible suggestion on stack overflow with no success.
When I run python --version the result :
Home-Macbook-Pro:~ pcmac$ python
WARNING: Python 2.7 is not recommended.
This version is included in macOS for compatibility with legacy software.
Future versions of macOS will not include Python 2.7.
Instead, it is recommended that you transition to using 'python3' from within Terminal.
Python 2.7.16 (default, Jun 5 2020, 22:59:21)
[GCC 4.2.1 Compatible Apple LLVM 11.0.3 (clang-1103.0.29.20) (-macos10.15-objc- on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> exit ()
How can I uninstall or force terminal to use Python version 3.8 please
Also the IDLE is running on old Python version 2.7.16
I had the same issue and this solution worked for me:
I am using macOS Catalina version 10.15.6 and used homebrew to install python 3.8.5.
All I did was type 'nano .zprofile' in terminal and then typing: alias python='python3' and saving it by hitting Ctrl+o and then Enter.

How to switch AWS CLI to Python 3.7 on macOS?

On macOS Mojave 10.14.6, have the following versions of python installed:
Python 2.7.16
Python 2.7.16 (default, May 17 2019, 18:32:33)
[GCC 4.2.1 Compatible Apple LLVM 10.0.1 (clang-1001.0.46.4)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
Python 3
Python 3.7.4 (v3.7.4:e09359112e, Jul 8 2019, 14:54:52)
[Clang 6.0 (clang-600.0.57)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
Installed AWS CLI using these steps:
curl "https://s3.amazonaws.com/aws-cli/awscli-bundle.zip" -o "awscli-bundle.zip"
unzip awscli-bundle.zip
sudo ./awscli-bundle/install -i /usr/local/aws -b /usr/local/bin/aws
Now, when I test aws from the command line using aws --version
aws-cli/1.16.247 Python/2.7.16 Darwin/18.7.0 botocore/1.12.237
Question(s):
Is this correct?
Is it supposed to be using Python 3.7.4 instead?
If so, how can I switch this over?
By default the installer will use whatever is in your path for python.
If you want to use Python 3, you need to run something like this to run the installer:
sudo /usr/local/bin/python3 awscli-bundle/install -i /usr/local/aws -b /usr/local/bin/aws
Replace /usr/local/bin/python3 with your path for Python 3 if it's different.
All of this said, if you have both Python environments installed, I'm not aware of any reason to prefer one version over the other for the AWS CLI tool.

With Python 2.7.15 on a MAC console, virtualenv creates an environment with a different version of Python

Here is an extract of my console in a Mac, as you can see the Python on the console is 2.7.15 but on the environment it becomes 2.7.10 which is an older version... any help on why and how to fix it would be most welcomed!
dhcp-18-57:Wakeup6 **jbs$ python**
**Python 2.7.15** (default, May 1 2018, 16:44:14)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()
dhcp-18-57:Wakeup6 jbs$ virtualenv env
New python executable in /Users/jbs/PycharmProjects/Wakeup6/env/bin/python
Installing setuptools, pip, wheel...done.
dhcp-18-57:Wakeup6 jbs$ source env/bin/activate
(env) dhcp-18-57:Wakeup6 **jbs$ python**
**Python 2.7.10** (default, Oct 23 2015, 19:19:21)
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()
If you installed python using Anaconda, then set up a new virtual environment for python 2.7.15 Then following directions in the Anaconda documentation, activate this virtual environment and you should be good to go.
If you didn't use Anaconda, just follow the directions for setting up a virtual environment on a Unix box. Then activate that environment and start working.
You can have multiple versions on your computer. Virtual environments allow you to run the version you want. I have virtual environments for python 2.7.13 and python 3.6.
If this doesn't work please let me know. I'll try to help.
Thank you all for your input. I finally figured out how to solve it. The difficult part was finding out how to locate the place where python 2.7.15 was installed which I'll leave intact in the response since I found it by trial and error looking in other places. I have not found a command that gives you the full path (perhaps an expert can tell us how to go from the laconic which python to the full path).
What I find interesting is that it does not really matter what the console uses when calling virtualenv. What matters is the version of Python used to install virtualenv which is the default version that will be used.
Essentially one has to use the -p option in virtualenv and make sure to find the right location where the desired version of python is.
dhcp-18--41:WakeUp8 jbs$ virtualenv -p /usr/local/Cellar/python#2/2.7.15/bin/python env
Running virtualenv with interpreter /usr/local/Cellar/python#2/2.7.15/bin/python
New python executable in /Users/jbs/PycharmProjects/WakeUp8/env/bin/python2.7
Also creating executable in /Users/jbs/PycharmProjects/WakeUp8/env/bin/python
Installing setuptools, pip, wheel...done.
dhcp-18-189-34-41:WakeUp8 jbs$ python
Python 2.7.15 (default, May 1 2018, 16:44:14)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> exit()
dhcp-18--41:WakeUp8 jbs$ pwd
/Users/jbs/PycharmProjects/WakeUp8
dhcp-18-189-34-41:WakeUp8 jbs$ source env/bin/activate
(env) dhcp-18-189-34-41:WakeUp8 jbs$ python
Python 2.7.15 (default, May 1 2018, 16:44:14)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.42.1)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>

What does GCC have to do with a python interpreter?

I just noticed this on my macintosh. Running $ python fires up an interpreter session with the following lines:
$ python2.7
Python 2.7.10 (default, Feb 6 2017, 23:53:20)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
The second line of the starting up text mentions GCC and clang versions.
How are these two related to the python interpreter? Given that python is an interpreted language, there should be no whisper of a compiler at all, so I was curious as to why this is shown.
Now here's the same thing with python3.6:
$ python3.6
Python 3.6.0 (v3.6.0:41df79263a11, Dec 22 2016, 17:23:13)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
This time there's no mention of clang. Why's that?
The CPython interpreter is itself written in C. It matters what compiler was used to convert the C code into a binary executable; behaviour and performance can differ in subtle ways, so it is mentioned in the banner.
You have two different Python binaries, the differences in the banner reflect differences in how those binaries where built. Since the Python 2.7 release is the one that comes bundled with OS X, it was built by Apple engineers using a different toolchain (using the clang compiler) from the Python 3.6 installation, which you must have installed separately (OS X doesn't include Python 3.6 yet). The latter was compiled with the GCC compiler.

MacPorts on Snow Leopard: Python install seems to succeed but doesn't install a non-system Python

I've installed Python via MacPorts. According to this question, the files in /opt/local/bin should run the "correct" Python version. However, all those files are symlinks to:
/opt/local/Library/Frameworks/Python.framework/Versions/2.6/bin/
Running them directly from that folder (using no symlinks) runs an Apple build of Python!
Python 2.6.6 (r266:84292, Jan 6 2011, 13:25:25)
[GCC 4.2.1 (Apple Inc. build 5664)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
For comparison, running /usr/bin/python shows a slightly different version:
Python 2.6.1 (r261:67515, Jun 24 2010, 21:47:49)
[GCC 4.2.1 (Apple Inc. build 5646)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>>
They're both Apple builds! How do I install the correct version?
There are no "Apple builds" except the system Python (which is 2.6.1 on Snow Leopard, afai can deduce). The ports install seems to have worked as expected in this case. The reference to Apple is a reference to which GCC that was used.
I think it is running the build you want.
macports install every thing in /opt/local. So /opt/local/bin/python is a macport distribution.
/usr/bin/python is pre-install python distribution that comes with mac os x.
The following line, is an information about gcc build which is used for building macport python distribution.
[GCC 4.2.1 (Apple Inc. build 5664)]
If you have multiple versions of macport python installed, you can select the version using python-select
sudo port install python-select sudo
python-select python26
Also to ensure that you use macport python you could add the following to the PATH
export PATH=/opt/local/bin:$PATH

Categories

Resources