On 03/09/2025 14:59, Mats Wichmann wrote:
On 9/3/25 07:20, Rob Cliffe wrote:
On 03/09/2025 00:01, Mats Wichmann wrote:
On 9/2/25 14:51, Rob Cliffe via Python-list wrote:
There are two roots here:
(1) it's not finding a prebuilt wheel. You can see that because
it's proposing to use the source distribution instead:
> Collecting matplotlib
> Using cached matplotlib-3.10.6.tar.gz (34.8 MB)
and so it, in the initial output.
I may be wrong, but I suspect that this is because I have attempted
to do the install multiple times. I.e. it didn't say this on the
first run.
(2) Although at this point all hope of success is often lost on
Windows, it's still going to try to compile things. It found gcc -
there are messages from g++ in the output. Last I know, Pybind11
only builds with the Microsoft compiler because it uses
msvc-specific types which gcc does not know about.
Since the matplotlib project definition provides wheels for Python
3.13 on Windows (not just the main Python, but also the
free-threaded versions), you need to figure out why the resolver
doesn't think there's anything applicable available.
Thanks for your reply, Mats, but I'm still lost.
Best wishes
Rob Cliffe
Thanks again Mats, I appreciate that you've done your best.
Sadly I have not been able to resolve the issue yet.
I can't tell you specifically how to diagnose why it's not finding
what you hope it would find. You might try these things:
# remove cached entries so you're resolving all from PyPI
pip cache purge
I tried this, it seems to make no difference.
# do a test install with some flags that *might* give you useful info:
pip -v install --dry-run --only-binary :all: --ignore-installed matplotlib
I'm not familiar with these pip options, but I tried this and got the
following output:
Using pip 25.2 from C:\Python313\Lib\site-packages\pip (python 3.13)
ERROR: Could not find a version that satisfies the requirement
matplotlib (from versions: none)
ERROR: No matching distribution found for matplotlib
It would take people with more pip experience to dig deeper.
I think the alternate manager "uv" may have more targeted debug
control for this scenario, but I don't promise, haven't used it that
much.
I'm sure somebody will pop up with comments if this is bad advice - I
tried to answer the question of what's happening but not sure how to
fix it.
I am somewhat surprised (whinge, whinge 🙁) that I got this problem
doing something completely normal
(installing a well-known package with a standard O/S and a standard
version of Python).
Can anyone else help, please?
Best wishes
Rob Cliffe
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