Get result of line above

Question

in this post it is explained, how to use the result of a previous code execution by using _, e.g.

>>> 5+5
10
>>> _
10
>>> _ + 5
15
>>> _
15

The question is inspired by languages like Mathematica, where you can easily call the result of the last line.

I notices, that this example does not work when you execute it all at ones, e.g.

5+5
_+5

Is there a corresponing way to calculate without defining new variables each time?

Edit: The role of _ has been understood. The question is, wether there is (can be/ can't be) a corresponding statement that reads the result of the last line within the same execution.

This is purely for quickly experimenting on the interactive CLI. In actual Python code you’d always use variables. — deceze, Mar 01 '20 at 08:00
You maybe would use variables in Python, but is there no other way? — Uwe.Schneider, Mar 01 '20 at 08:02
`_` will store the value of the last evaluated expression in the IDLE. It has nothing to do with "lines" per se — Hymns For Disco, Mar 01 '20 at 08:05

score 3 · Accepted Answer · answered Mar 01 '20 at 08:06

This behavior of _ is only available in REPL. _ holds the output of that the last expression evaluated to. It should be noted, if the previous expression produced a TRACEBACK, _ will hold the last valid output. You could also chain _ upto three times (in IPython), to go fetch the 3rd last output:

>>> 5
5
>>> 6
6
>>> 7
7
>>> ___
5
>>> __
7
>>> _
7

If you use it in actual scripts, you can treat it _ as a variable name (not recommended, if you plan to use the variable), for example:

_ = 10
print(_)

# will print 10

But the behavior you get at REPL can't be emulated in an actual script.

Get result of line above

1 Answers1