Python: Boolean return if arbitrary element is in arbitrary list

Question

Noob wondering how to improve his code.

a, b, c = string.split(enteredDate, "/")

m31s = [1, 3, 5, 7, 8, 10, 12]
m30s = [4, 6, 9, 11]

for x in range(len(m31s)):
    x = int(m31s[x])
    if x != int(a) and b != 31:
         print "Invalid date."
for x in range(len(m30s)):
    et cetera...

In case it isn't clear, I am testing an inputted date to see if it is valid. This is only part of the program. The main question is: what is the best way to test if an element matches ANY element in a list?

My method works... But, I suspect there is a better way to do this. I said boolean in the title because I envision something like:

if secretCode(m31s, int(a)) == True:

Could be a pipedream. Just curious.

Thanks to anyone who takes the time to help.

31s is not a valid variable name. variable names can not start with a digit, though they can contain digits. — unutbu
– unutbu, Commented Oct 19, 2012 at 20:09
Yeah, you're exactly right. I learned that when I ran this earlier--forgot to make the changes in my post. Good catch. — d0rmLife
– d0rmLife, Commented Oct 19, 2012 at 20:13

Matthew Adams · Accepted Answer · 2012-10-19 20:08:46Z

6

You can use the syntax if elem in list. For example:

>>> if 1 in [1,2,3,4,5]:
...     print 'found 1'
... 
found 1

answered Oct 19, 2012 at 20:08

Matthew Adams

10.3k3 gold badges31 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

d0rmLife Over a year ago

Thanks. This will be prove quite useful!

d0rmLife Over a year ago

BTW I chose your answer because it answered the specific question. Other responses also provided excellent insights.

Matthew Adams Over a year ago

Agreed, they're very helpful. You should upvote them to thank them. (I'm about upvote both as well.)

Daniel · Accepted Answer · 2012-10-19 22:03:17Z

2

You should use python datetime library.

try:
    datetime.datetime.strptime(enteredDate, "%m/%d/%Y")
except:
    print 'Invalid date'

edited Oct 19, 2012 at 22:03

answered Oct 19, 2012 at 20:19

Daniel

31.8k19 gold badges87 silver badges145 bronze badges

3 Comments

unutbu Over a year ago

+1 for datetime. In the OP's code, a appears to be the month, b appears to be a date (31). So perhaps he wants %m/%d/%Y.

d0rmLife Over a year ago

Thanks for introducing me to this library. BTW: seems like it should be "%m/%d/%Y"

d0rmLife Over a year ago

Wow, missed your comment unutbu. Sorry for the repetition.

hochl · Accepted Answer · 2012-10-19 20:24:11Z

1

I suggest:

replace
```
   a, b, c = string.split(enteredDate, "/")
```
with
```
   a, b, c = enteredDate.split("/")
```
Not that it matters much, but the first version needs to import the string module, the second not.
replace int(m31s[x]) with m31s[x] (you know those are int already, why the extra int( ... ) then?
in case secretCode( ... ) returns true or false you can simply write if secretCode( ... ):, no need to compare with == True.
instead of calling int(a), int(b) or int(c) you can simply write a, b, c = map(int, enteredDate.split("\")) and forget about those int( ... ) later since you know they are int. Additionally, if those are not int you will immediately get an exception without unnecessarily progressing in your code.

edited Oct 19, 2012 at 20:24

answered Oct 19, 2012 at 20:18

hochl

13.1k10 gold badges58 silver badges92 bronze badges

1 Comment

d0rmLife Over a year ago

Thanks for all the style suggestions. Seriously--it is difficult to get these sorts of minor corrections, which are invaluable to me. If only I could get them more often!

Collectives™ on Stack Overflow

Python: Boolean return if arbitrary element is in arbitrary list

3 Answers 3

3 Comments

3 Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

3 Comments

3 Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related