Hey.
You can use expon:
http://nbviewer.ipython.org/github/amueller/pydata-nyc-advanced-sklearn/blob/master/Chapter%203%20-%20Randomized%20Hyper%20Parameter%20Search.ipynb
(it has a scale parameter)

Andy


On 04/07/2015 05:16 PM, Arnaud Fouchet wrote:
Hello,

I have a little question about Random Search vs Grid Search. I am used to grid search over parameter increasing exponentially (lambda = 0.01, 0.1, ... 1000). When you use randomized search, what type of distribution do you use ? If I use an uniform distribution, I would test hyper-parameter values that are in the same order of magnitude.

Thank you,

Arnaud

2015-04-07 21:28 GMT+02:00 Andreas Mueller <t3k...@gmail.com <mailto:t3k...@gmail.com>>:

    I talks about it a bunch here:
    https://www.youtube.com/watch?v=0wUF_Ov8b0A

    The paper is here: http://www.jmlr.org/papers/v13/bergstra12a.html

    I'd be interested in the blog post.
    Really I don't think searching over losses and regularization will
    give you much usually.
    I have not really seen any experienced machine learner do it.


    On 04/07/2015 03:01 PM, Jason Wolosonovich wrote:

    Hi Roberto,

    I’m no expert by any means, but I was reading a blog post the
    other day that talked about using Random Search vs Grid Search.
    The gist of the article is that, since you can feed distributions
    to Random Search and it selects values randomly over the number
    of iterations you choose,  it is a better initial choice when
    you’re not sure which parameters/combinations to use (which is
    usually my case J) and you’ll end up with Random Search finding
    more useful parameters faster than if you tell Grid Search to
    search over combinations (some of which may have no potential to
    help you). Then when you see the results of the Random Search,
    you can use that information to search a narrower range of
    values/parameters (a finer grid) exhaustively using Grid Search.

    Unfortunately, I thought I bookmarked the article but I can’t
    find it. I’ll keep looking though and send it out if I do.

    Additionally, the docs for the individual estimators in Sklearn
    tell you what parameters are not valid with each other, so you
    wouldn’t want to put those parameters together in your param_grid
    dictionary. For your dictionary (as others have already
    mentioned) just make sure that you only provide options in each
    of your dictionaries that can be used together. You can pass a
    list of dictionaries to param_grid like Sebastian just demonstrated.

    Check the links below as well, Random Search comes up with just
    about the same results as Grid Search, but faster/more
    efficiently. Hope this helps.

    Scikit Docs:

    http://scikit-learn.org/stable/modules/grid_search.html#grid-search-tips

    
http://scikit-learn.org/stable/auto_examples/model_selection/randomized_search.html#example-model-selection-randomized-search-py

    -Jason

    *From:*Pagliari, Roberto [mailto:rpagli...@appcomsci.com]
    *Sent:* Tuesday, April 07, 2015 9:24 AM
    *To:* scikit-learn-general@lists.sourceforge.net
    <mailto:scikit-learn-general@lists.sourceforge.net>
    *Subject:* [Scikit-learn-general] CV with SVM

    not all combinations of cost/loss functions and dual are possible
    with SVM.

    when performing grid search with CV, does sklearn skip invalid
    combinations?

    Thank you,



    
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