How do I clone a conda environment from one python release to another?

Question

I have a python 2.7 conda environment and would like to create an equivalent environment with python 3.4. I am aware of the `--clone` option when creating environments, but it won't accept additional arguments, like `python=3.4`. Is there a way to do this automatically? I thought about trying to use the output from `conda list --export`, but that also encodes the python release.

Accepted Answer

One way would be to

```
conda list --export > exported-packages.txt
```

And then edit that file to remove the last part of each package with the `py27_0` parts (you might also want to remove the versions, in case some version of a package doesn't have a Python 3 version). Then

```
conda create -n py3clone --file exported-packages.txt
```

Another idea would be to clone the environment:

```
conda create -n clonedenv --clone oldenv
conda install -n clonedenv python=3.4
conda update -n clonedenv --all
```

Note that obviously both of these will fail if you have some package that doesn't have a Python 3 version.

How do I clone a conda environment from one python release to another?

Solution

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