Comparing variable types

[Kill Bill]

type(i) == "<type 'float'>"
this always returns false. How come?
type(i)returns <type 'float'> if i is a float so why isn't == working?

[KefX]

>type(i) == "<type 'float'>"

this always returns false. How come?
type(i)returns <type 'float'> if i is a float so why isn't == working?

Use isinstance(), like this:
isinstance(i, float)
This will return True if i is a float, False if not.

- Kef

[Emile van Sebille]

"Kill Bill" <bi**@kill.com> wrote in message
news:bn*************@ID-198839.news.uni-berlin.de...

type(i) == "<type 'float'>"
This compares the current type of i to type("string"), which is <type
'str'>.

You can do:

i = 1.3
type(i) == "<type 'float'>"
False str(type(i)) == "<type 'float'>" True

this always returns false. How come?
type(i)returns <type 'float'> if i is a float so why isn't == working?

What you probably want is:
import types
type(i) == types.FloatType True

Emile van Sebille
em***@fenx.com

[Kill Bill]

Can you tell me where you found that method in the docs? I'm having trouble
navigating them, the java docs are so much easier to look at.

"KefX" <ke**********@aol.comNOSPAM> wrote in message
news:20***************************@mb-m07.aol.com...

type(i) == "<type 'float'>"
this always returns false. How come?
type(i)returns <type 'float'> if i is a float so why isn't == working?

Use isinstance(), like this:
isinstance(i, float)
This will return True if i is a float, False if not.

- Kef

[KefX]

>What you probably want is:

import types
type(i) == types.FloatTypeTrue

Using isinstance() as I described earlier is probably better because I think it
works better with the idea of unifying types and classes.

- Kef

[KefX]

>Can you tell me where you found that method in the docs?

It's a builtin, meaning it's in module __builtin__. You'll find them in the
library reference near the top under "built-in functions" or some such.

- Kef

[Andrew Bennetts]

On Sat, Oct 25, 2003 at 10:36:03PM -0400, Kill Bill wrote:

type(i) == "<type 'float'>"
this always returns false. How come?
type(i)returns <type 'float'> if i is a float so why isn't == working?

Because "<type 'float'>" is a string :)

You want
import types
type(i) == types.FloatType

or
type(i) == type(1.0)

or in 2.2 and later you can simply do
type(i) == float

-Andrew.

[Andrew Bennetts]

On Sat, Oct 25, 2003 at 10:50:21PM -0400, Kill Bill wrote:

Can you tell me where you found that method in the docs? I'm having trouble
navigating them, the java docs are so much easier to look at.

Library Reference, section 2.1: Built-in Functions
http://python.org/doc/current/lib/built-in-funcs.html

-Andrew.

[Kill Bill]

Where can I find all the methods for Dictionaries? They list some here, but
is that all of them?
http://www.python.org/doc/2.3.2/tut/...00000000000000
I think it is, but I don't like how its written. I want it to be written
you know by method, constuctors, like in the Java API. Anyone know what I'm
talking about? Its so quick to skim through the API to see which method you
are looking for. Not the case here.

"Andrew Bennetts" <an***************@puzzling.org> wrote in message
news:ma************************************@python .org...

On Sat, Oct 25, 2003 at 10:50:21PM -0400, Kill Bill wrote:

Can you tell me where you found that method in the docs? I'm having trouble navigating them, the java docs are so much easier to look at.

Library Reference, section 2.1: Built-in Functions
http://python.org/doc/current/lib/built-in-funcs.html

-Andrew.

[Andrew Bennetts]

On Sun, Oct 26, 2003 at 12:44:20AM -0400, Kill Bill wrote:

Where can I find all the methods for Dictionaries? They list some here, but
is that all of them?
http://www.python.org/doc/2.3.2/tut/...00000000000000
I think it is, but I don't like how its written. I want it to be written
you know by method, constuctors, like in the Java API. Anyone know what I'm
talking about? Its so quick to skim through the API to see which method you
are looking for. Not the case here.

Again, you can find it in the library reference:
http://python.org/doc/current/lib/typesmapping.html

Although it isn't clear until you've read that that dictionaries are a
"mapping type", if you look in the index you'll find that both "dictionary
object" and "dictionary type, operations on" point you to that section.

I think you probably want to familiarise yourself with all of section 2 of
the Library Reference.

-Andrew.

[David Eppstein]

In article <bn*************@ID-198839.news.uni-berlin.de>,
"Kill Bill" <bi**@kill.com> wrote:

Where can I find all the methods for Dictionaries? They list some here, but
is that all of them?
http://www.python.org/doc/2.3.2/tut/...00000000000000
I think it is, but I don't like how its written. I want it to be written
you know by method, constuctors, like in the Java API. Anyone know what I'm
talking about? Its so quick to skim through the API to see which method you
are looking for. Not the case here.

Try typing help(dict) to the Python interpreter.

--
David Eppstein http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science

[David Eppstein]

In article <ma************************************@python.org >,
Andrew Bennetts <an***************@puzzling.org> wrote:

On Sat, Oct 25, 2003 at 10:36:03PM -0400, Kill Bill wrote:

type(i) == "<type 'float'>"
this always returns false. How come?
type(i)returns <type 'float'> if i is a float so why isn't == working?

Because "<type 'float'>" is a string :)

You want
import types
type(i) == types.FloatType

or
type(i) == type(1.0)

or in 2.2 and later you can simply do
type(i) == float

But it's almost always preferable to do
isinstance(i,float)
because that allows subclasses of float to be used. If you really have
to test whether i is an unsubclassed float,
type(i) is float
would be a better choice than
type(i)==float
as it more accurately expresses the intent that only the precise float
type will be allowed.

--
David Eppstein http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science

[Peter Hansen]

Emile van Sebille wrote:

"Kill Bill" <bi**@kill.com> wrote in message
news:bn*************@ID-198839.news.uni-berlin.de...

type(i) == "<type 'float'>"

This compares the current type of i to type("string"), which is <type
'str'>.

(Minor correction) Actually it compares it to the actual string
containing the letters "<type 'float'>", which is of course going
to get one nowhere.

The above would have worked if the OP had used

repr(type(i)) == "<type 'float'>"

but that is the absolute worst way of doing this...

-Peter

[John J. Lee]

"Kill Bill" <bi**@kill.com> writes:

"KefX" <ke**********@aol.comNOSPAM> wrote in message
news:20***************************@mb-m07.aol.com... [...]

Use isinstance(), like this:

[...] Can you tell me where you found that method in the docs? I'm having trouble

[...]

Rule of thumb: If you can't find it, it's in section 2 of the library docs.
John

[Cameron Laird]

In article <ep****************************@news.service.uci.e du>,
David Eppstein <ep******@ics.uci.edu> wrote:

In article <bn*************@ID-198839.news.uni-berlin.de>,
"Kill Bill" <bi**@kill.com> wrote:

Where can I find all the methods for Dictionaries? They list some here, but
is that all of them?
http://www.python.org/doc/2.3.2/tut/...00000000000000
I think it is, but I don't like how its written. I want it to be written
you know by method, constuctors, like in the Java API. Anyone know what I'm
talking about? Its so quick to skim through the API to see which method you
are looking for. Not the case here.

Try typing help(dict) to the Python interpreter.