You’ve discovered a bug or something else you want to change in matplotlib .. — excellent!
You’ve worked out a way to fix it — even better!
You want to tell us about it — best of all!
masterbranch clean of edits that have not been merged to the main matplotlib development repo. Your
masterthen will follow the main matplotlib repository.
masterbranch or maintenance tracking branches into your feature branch. If you need to include commits from upstream branches (either to pick up a bug fix or to resolve a conflict) please rebase your branch on the upstream branch.
This way of working really helps to keep work well organized, and in keeping history as clear as possible.
See — for example — linux git workflow.
git checkout -b my-new-feature master
This will create and immediately check out a feature branch based on
master. To create a feature branch based on a maintenance branch,
git fetch origin git checkout -b my-new-feature origin/v1.0.x
Generally, you will want to keep this also on your public GitHub fork
of matplotlib. To do this, you git push this new branch up to your GitHub
repo. Generally (if you followed the instructions in these pages, and
by default), git will have a link to your GitHub repo, called
origin. You push up to your own repo on GitHub with:
git push origin my-new-feature
You will need to use this exact command, rather than simply
push every time you want to push changes on your feature branch to
your GitHub repo. However, in git >1.7 you can set up a link by
git push --set-upstream origin my-new-feature
and then next time you need to push changes to your branch a simple
git push will suffice. Note that
git push pushes out all
branches that are linked to a remote branch.
# hack hack git add my_new_file git commit -am 'NF - some message' git push
Make some changes
See which files have changed with
git status (see git status).
You’ll see a listing like this one:
# On branch ny-new-feature # Changed but not updated: # (use "git add <file>..." to update what will be committed) # (use "git checkout -- <file>..." to discard changes in working directory) # # modified: README # # Untracked files: # (use "git add <file>..." to include in what will be committed) # # INSTALL no changes added to commit (use "git add" and/or "git commit -a")
Check what the actual changes are with
git diff (git diff).
Add any new files to version control
git add new_file_name (see
To commit all modified files into the local copy of your repo,, do
git commit -am 'A commit message'. Note the
-am options to
m flag just signals that you’re going to type a
message on the command line. The
a flag — you can just take on
faith — or see why the -a flag? — and the helpful use-case
description in the tangled working copy problem. The git commit manual
page might also be useful.
To push the changes up to your forked repo on GitHub, do a
It’s a good idea to consult the Pull request checklist to make sure your pull request is ready for merging.
When working on a PR, changes may occur in the parent branch (usually master).
This can lead to conflict with changes in your branch. The conflicts can be
trivial: for example both the parent branch and your branch add an entry to
the top of
CHANGELOG. Git can not unambiguously tell what to do with both
changes (should one go above the other? if so, which order? should it try to
merge them?) so it declares the branches can not be merged
cleanly. GitHub can only automatically merge PR without conflicts, so you will
need to manually ‘rebase’. This is the process of updating your branch with
upstream changes, and resolving conflicts.
In git, rebasing is a mild form of re-writing history: it effectively forwards all your commits to the updated upstream commit. For a much more detailed explanation (with pictures!) see this nice write up. The NumPy team has also documented how to do this. In general, re-writing history, particularly published history, is considered bad practice, but in this case it is very useful.
The following example assumes that the remote of _your_ GitHub
repository is called
origin and the remote of the official
repository is called
The first step is to make sure that your local copy of the upstream repository is up-to-date:
$ git fetch matplotlib
This updates your local copy of the repository, but does not change any files in your working copy. Next, switch to the branch that you want to update:
$ git checkout backend_plt_refactor
You are now ready to start the rebase of your branch onto the target
parent branch, in this case
$ git rebase matplotlib/master
and git will then give a bunch of feed back:
First, rewinding head to replay your work on top of it... Applying: first steps to extract FigureManager* and friends from pyplot Applying: split backend_qt4 into two parts, with and without Gcf ... Applying: pep8 clean up on backend_gtk3.py Using index info to reconstruct a base tree... M lib/matplotlib/backends/backend_gtk3.py Falling back to patching base and 3-way merge... Auto-merging lib/matplotlib/backends/backend_gtk3.py CONFLICT (content): Merge conflict in lib/matplotlib/backends/backend_gtk3.py Failed to merge in the changes. Patch failed at 0013 pep8 clean up on backend_gtk3.py The copy of the patch that failed is found in: /home/tcaswell/other_source/matplotlib/.git/rebase-apply/patch When you have resolved this problem, run "git rebase --continue". If you prefer to skip this patch, run "git rebase --skip" instead. To check out the original branch and stop rebasing, run "git rebase --abort".
We see that a number of commits could be cleanly applied to the tip of
matplotlib/master. However, git may eventually hit a commit that
had conflicts: in the example above, this happens in the file
lib/matplotlib/backends/backend_gtk3.py). For more verbose
$ git status You are currently rebasing branch 'backend_plt_refactor' on 'e6f8993'. (fix conflicts and then run "git rebase --continue") (use "git rebase --skip" to skip this patch) (use "git rebase --abort" to check out the original branch) Unmerged paths: (use "git reset HEAD <file>..." to unstage) (use "git add <file>..." to mark resolution) both modified: lib/matplotlib/backends/backend_gtk3.py no changes added to commit (use "git add" and/or "git commit -a")
This tells you exactly where the conflict (caused by the target branch and your commits modifying the same lines of code) is and provides some advice on how to proceed. Opening up the file in question, you will see blocks that look something like this:
<<<<<<< HEAD ======= self.__dict__.clear() # Is this needed? Other backends don't have it. >>>>>>> pep8 clean up on backend_gtk3.py
The block of code between
======= is the code on the
target branch (in this case nothing) and the code between
>>>>>>> is the code in the commit you are trying to rebase. The
rest of the code is either the same or the diff can be unambiguously
applied. You need to determine how to resolve the conflict (in this
case, the code on HEAD is correct). Once you have resolved all the
add the file to the index:
$ git add lib/matplotlib/backends/backend_gtk3.py
Repeat this for all of the files that have conflicts. When you are done with that you can check the status:
$ git status rebase in progress; onto e6f8993 You are currently rebasing branch 'backend_plt_refactor' on 'e6f8993'. (all conflicts fixed: run "git rebase --continue") Changes to be committed: (use "git reset HEAD <file>..." to unstage) modified: lib/matplotlib/backends/backend_gtk3.py
which shows us that we have resolved all of the conflicts with this commit and can continue:
$ git rebase --continue
You now iterate the until you have made it through all of the commits which have conflicts. Once you have successfully rebased your branch, be sure to re-run the tests to make sure everything is still working properly.
Your branch is now rebased, however, because of the way git
determines the hash of each commit, it now shares no commits with your
old branch published on GitHub so you can not push to that branch as
you would when simply adding commits. In order to publish your newly
rebased (and tested!) branch you need to use the
$ git push --force origin
which will _replace_ all of the commits under your branch on GitHub with the new versions of the commit.
Congratulations, you have rebased your branch!
This updates your working copy from the upstream matplotlib GitHub repo.
# go to your master branch git checkout master # pull changes from github git fetch matplotlib # merge from matplotlib git merge --ff-only matplotlib/master
We suggest that you do this only for your
master branch, and leave
your ‘feature’ branches unmerged, to keep their history as clean as
possible. This makes code review easier:
git checkout master
Make sure you have done Linking your repository to the upstream repo.
Merge the upstream code into your current development by first pulling the upstream repo to a copy on your local machine:
git fetch upstream
then merging into your current branch:
git merge --ff-only upstream/master
--ff-only option guarantees that if you have mistakenly
committed code on your
master branch, the merge fails at this point.
If you were to merge
upstream/master to your
would start to diverge from the upstream. If this command fails, see
the section on accidents.
The letters ‘ff’ in
--ff-only mean ‘fast forward’, which is a
special case of merge where git can simply update your branch to point
to the other branch and not do any actual merging of files. For
master and other integration branches this is exactly what you
Some people like to keep separate local branches corresponding to the
maintenance branches on GitHub. At the time of this writing,
is the active maintenance branch. If you have such a local branch,
treat is just as
master: don’t commit on it, and before starting
new branches off of it, update it from upstream:
git checkout v1.0.x git fetch upstream git merge --ff-only upstream/v1.0.x
But you don’t necessarily have to have such a branch. Instead, if you are preparing a bugfix that applies to the maintenance branch, fetch from upstream and base your bugfix on the remote branch:
git fetch upstream git checkout -b my-bug-fix upstream/v1.0.x
If you have accidentally committed changes on
git merge --ff-only fails, don’t panic! First find out how much
you have diverged:
git diff upstream/master...master
If you find that you want simply to get rid of the changes, reset
master branch to the upstream version:
git reset --hard upstream/master
As you might surmise from the words ‘reset’ and ‘hard’, this command actually causes your changes to the current branch to be lost, so think twice.
If, on the other hand, you find that you want to preserve the changes, create a feature branch for them:
git checkout -b my-important-changes
my-important-changes points to the branch that has your
changes, and you can safely reset
master as above — but
make sure to reset the correct branch:
git checkout master git reset --hard upstream/master
git checkout master # delete branch locally git branch -D my-unwanted-branch # delete branch on GitHub git push origin :my-unwanted-branch
Note the colon
my-unwanted-branch. See also: