所以我跑:
$ gem install rails --version 3.0.1
Successfully installed rails-3.0.1
1 gem installed
Installing ri documentation for rails-3.0.1...
Installing RDoc documentation for rails-3.0.1...
然后我得到错误:
$ rails -v
/usr/local/rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:1637:in `raise_if_conflicts': Unable to activate rails-3.0.1, because bundler-1.1.4 conflicts with bundler (~> 1.0.0) (Gem::LoadError)
from /usr/local/rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems/specification.rb:746:in `activate'
from /usr/local/rvm/rubies/ruby-1.9.3-p125/lib/ruby/site_ruby/1.9.1/rubygems.rb:1232:in `gem'
from /usr/local/rvm/gems/ruby-1.9.3-p125@rails3tutorial/bin/rails:18:in `<main>'
from /usr/local/rvm/gems/ruby-1.9.3-p125@rails3tutorial/bin/ruby_noexec_wrapper:14:in `eval'
from /usr/local/rvm/gems/ruby-1.9.3-p125@rails3tutorial/bin/ruby_noexec_wrapper:14:in `<main>'
这是一个列表清单:
a = [[1,2,3],[4,5,6],[7,8,9]]
要从变量'a'中获取数字4,我会调用a[1][0]但如果不是数字,那么如果它们是列表:
a = [[[1],[2],[3]], [[4],[5],[6]], [[7],[8],[9]]]
现在得到4号,它会是a[0][1][0]或a[1][0][0]？
我知道我可以用它来解决这个问题,但我正在寻找一个解释Python如何实际接近从列表列表中获取数字的操作顺序的方法.