CODEWITHSUNDEEP
pythonipython
Tyler Wood
Tyler Wood

Reputation: 1967

How to access a variable in IPython from a program executed by %run

I have a program like this:

if __name__=="__main__":
  foo = expensiveDataProcessClass(filepath)

  y = foo.doStuff()
  y = foo.doOtherStuff()

I'm testing things out as a I build it in ipython with the %run myprogram command.

After it's running, since it takes forever, I'll break it with ctrl+C and go rewrite some stuff in the file.

Even after I break it, though, IPython has foo stored.

>type(foo) 
__main__.expensiveDataProcessClass

I'm never having to edit anything in foo, so it would be cool if I could update my program to first check for the existence of this foo variable and just continue to use it in IPython rather than doing the whole creation process again.

Upvotes: 1

Views: 197

Answers (1)

aruisdante
aruisdante

Reputation: 9075

You could first check for the variable's existence, and only assign to it if it doesn't exist. Example:

if __name__=="__main__":
    if not "foo" in globals()
        foo = expensiveDataProcessClass(filepath)

However, this won't actually work (in the sense of saving a foo assignment). If you read IPython's doc on the %run magic, it clearly states that the executed program is run in its own namespace, and only after program execution are its globals loaded into IPython's interactive namespace. Every time you use %run it will always not have foo defined from the program's prospective.

Upvotes: 1

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