how do you check if variable is equal in python

Question

I have a line array that values in position 5 can be either of these values:

"Tablespace Free Space (MB)", "Tablespace Space Used (%)"

if line[5] is any of these I need to do some extra work.

I have tried this:

if (line[5] in ("Tablespace Space Used (%)")|("Tablespace Free Space (MB)"))

    # some other code here

I keep getting this error:

    if (line[5] in ("Tablespace Space Used (%)"|"Tablespace Free Space (MB)"))
                                                                             ^
SyntaxError: invalid syntax

You need to add a ':' at the end of your if statement. For example: if (line[5] in ("Tablespace Space Used (%)", "Tablespace Free Space (MB)"): — Andrew
– Andrew, Commented Feb 11, 2015 at 21:08

Martijn Pieters · Accepted Answer · 2015-02-11 21:23:05Z

3

You were missing the : at the end of your if statement.

However, you are using invalid syntax for your test too; it'll lead to a runtime error (TypeError: unsupported operand type(s) for |: 'str' and 'str'). You want to create a tuple, or a set of strings to test against, not use |:

if line[5] in ("Tablespace Space Used (%)", "Tablespace Free Space (MB)"):

or

if line[5] in {"Tablespace Space Used (%)", "Tablespace Free Space (MB)"}:

The latter is technically more efficient, except if you are using Python 2 where the set isn't optimised into a constant the way the tuple would be in either version of the language. Using {...} to create a set requires Python 2.7 or newer.

edited Feb 11, 2015 at 21:23

answered Feb 11, 2015 at 21:09

Martijn Pieters

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2 Comments

user1471980 Over a year ago

@martinPeiters, I get this error: if line[5] in {"Tablespace Space Used (%)","Tablespace Free Space (MB)"}: ^ SyntaxError: invalid syntax

Martijn Pieters Over a year ago

@user1471980: What version of Python are you using? {...} for sets requires Python 2.7 or up.

Jonathan Epstein · Accepted Answer · 2015-02-11 23:21:02Z

1

You use == to check equality

4 == 2*2
True

To use an if statement, conclude the line with a ':'

if line[5] in {'Tablespace Space Used (%)', 'Tablespace Free Space (MB)'}:
   do x

edited Feb 11, 2015 at 23:21

answered Feb 11, 2015 at 21:10

Jonathan Epstein

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7 Comments

Martijn Pieters Over a year ago

why are you using in still instead of ==?

Jonathan Epstein Over a year ago

didn't see the OP's statement 'if line[5] is any of these I need to do some extra work.' will amend.

Martijn Pieters Over a year ago

Sure, but why not use a membership test still?

Jonathan Epstein Over a year ago

Could you elucidate? My understanding is that '==' is a membership test. docs.python.org/2/reference/…

Martijn Pieters Over a year ago

No, == tests for equality. in tests for membership. As in something in ('valueA', 'valueB) (which is implemented by testing for equality against each element in turn) or `something in {'valueA', 'valueB'} (which uses a hash table and equality testing for a more efficient membership test).

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