python if...elif always not working

Question

Sorry for posting such a naive question, but I'm just not able to figure this out. I have written following conditional statements:

if taxon == "Bracelets":
    catId = "178785"
elif taxon == "Kids Earrings" or "Earrings":
    catId = "177591"
elif taxon == "Mangalsutras":
    catId = "177595"
elif taxon == "Necklaces" or "Necklace Sets":
    catId = "177597"
elif taxon == "Kids Pendants" or "Pendants":
    catId = "177592"
elif taxon == "Pendant Sets":
    catId = "177593"
elif taxon == "Anklets":
    catId = "178788"
elif taxon == "Toe Rings":
    catId = "178787"
elif taxon == "Rings":
    catId = "177590"
else:
    print "no match\n"

But no matter what the value of taxon is, its always falling in the second condition i.e.

elif taxon == "Kids Earrings" or "Earrings":
    catId = "177591"

and therefore, the value of catId remains 177591.

`elif taxon == "Kids Earrings" or taxon == "Earrings":` otherwise the 2nd condition will always be true — reto, Dec 17 '13 at 12:14
@MartijnPieters : True. But, it was tough to find it as the name of the question does not suggest anything abt the content — nish, Dec 17 '13 at 12:22
That's alright, this is an issue many beginners run into without realizing what is going wrong. — Martijn Pieters, Dec 17 '13 at 12:23

YXD · Accepted Answer · 2013-12-17T12:50:16.783

This should be

elif taxon == "Kids Earrings" or taxon == "Earrings":

Your original code tests the truth value of "Earrings" rather than whether taxon has the value "Earrings"

>>> bool("Earrings")
True

A better way to structure this is with a dictionary:

id_map = {}
id_map["Bracelets"] = "178785"
id_map["Earrings"] = "177591"
id_map["Kids Earrings"] = "177591"
# etc

then later you can do

id_map[taxon]

This also lends itself better to storage in a configuration file or database, to avoid hard-coding the values in your Python code.

score 7 · Answer 2 · answered Dec 17 '13 at 12:16

Others have already given the syntactical answer to your problem.

My answer is to change this ugly code to use a dictionary lookup. For example:

taxes = {"Bracelets": 178785, "Necklaces": 177597, "Necklace Sets": 177597}
#etc

Then you use

catId = taxes[taxon]

score 3 · Answer 3 · answered Dec 17 '13 at 12:14

3

Use this idiom:

elif taxon in ("Kids Earrings", "Earrings"):

answered Dec 17 '13 at 12:14

David Zwicker

23,581
6
62
77

That's actually can cause some problems i think, if taxon is "Kids" for example. – Kobi K Dec 17 '13 at 12:16
2

It will not cause problem. – Prashant Gaur Dec 17 '13 at 12:18
You are right +1, I didn't know about that option. – Kobi K Dec 17 '13 at 12:22

Kobi K · Answer 4 · 2013-12-17T12:19:57.767

The problem is that it's always true since it evaluates for Boolean True, it checks if the string is empty.

Change to:

if taxon == "Bracelets":
    catId = "178785"
elif taxon == "Kids Earrings" or taxon == "Earrings":
    catId = "177591"
elif taxon == "Mangalsutras":
    catId = "177595"
elif taxon == "Necklaces" or taxon == "Necklace Sets":
    catId = "177597"
elif taxon == "Kids Pendants" or taxon == "Pendants":
    catId = "177592"
elif taxon == "Pendant Sets":
    catId = "177593"
elif taxon == "Anklets":
    catId = "178788"
elif taxon == "Toe Rings":
    catId = "178787"
elif taxon == "Rings":
    catId = "177590"
else:
    print "no match\n

In a personal note i would use python dict is really good instead of if else:

options = {"option1": "value1", "option2": "value2".....}

score 1 · Answer 5 · answered Dec 17 '13 at 12:15

This condition:

taxon == "Kids Earrings" or "Earrings"

looks like

(taxon == "Kids Earrings") or "Earrings"

which is always true because "Earrings" evaluates true (is a non-empty string).

You'd like to do:

taxon in ("Earrings, "Kids Earrings")

or just write several conditions:

taxon == "Earrings" or taxon == "Kids Earrings"

or perhaps:

taxon.endswith("Earrings")

score 1 · Answer 6 · answered Dec 17 '13 at 12:15

1

Use

elif taxon in ("Kids Earrings", "Earrings"):

answered Dec 17 '13 at 12:15

Prashant Gaur

9,540
10
49
71

score 0 · Answer 7 · answered Dec 17 '13 at 12:15

0

the second condition isn't checked against a variable. like this it makes no sense! try it this way:

...
elif taxon == "Kids Earrings" or taxon == "Earrings":
    catId = "177591"
...

answered Dec 17 '13 at 12:15

PrR3

1,250
1
18
26

python if...elif always not working

7 Answers7