finding key in dict using try except

Question

My function is:

def searchstock():  
dictionary=calcreturn(dictionize(tickers(openfile()),pairslist()))
inp=raw_input("What is the stock ticker? ")
while True:
    try:
        dictionary[inp]
        break
    except KeyError: 
        print("Ticker not found. Please input again ")

print(inp, dictionary[inp])

the try/except doesnt work. I'm trying to see if a user input is in the dictionary keys and then return the key and respective value

If imp is not in the dictionary, why would this be an infinite loop?

http://stackoverflow.com/questions/1602934/check-if-a-given-key-already-exists-in-a-dictionary — Alagappan Ramu, May 06 '13 at 23:21
you should not modify your original question ... as now it looks like every answer just copied and pasted what you had (which is not the case) — Joran Beasley, May 06 '13 at 23:44

Joran Beasley · Answer 1 · 2013-05-06T23:26:49.963

2

just

inp=raw_input("What is the stock ticker? ")
try:
   dictionary[inp]
   break; #exit loop
except KeyError:
   print "Nope!"

you will also need to break out of your while True loop

also if you are using py2x you will want to use raw_input instead of input

edited May 06 '13 at 23:26

answered May 06 '13 at 23:21

Joran Beasley

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NameError: name 'BIG' is not defined – user2356391 May 06 '13 at 23:22
thats a different problem caused by using `input` in python 2.x instead of `raw_input` – Joran Beasley May 06 '13 at 23:26
The problem with the code is NameError: name 'BIG' is not defined – user2356391 May 06 '13 at 23:27
1

@user2356391 when you do a normal 'input' in Python, if you enter a value like 'BIG' it is considered to be an object name. Here it is not defined. So as suggested by JoranBeasley change it to raw_input() and your code will work like a charm. – Alagappan Ramu May 06 '13 at 23:40

Alagappan Ramu · Answer 2 · 2013-05-06T23:41:38.663

0

listkeys in your code is a list and not a dictionary. Finding an element in a list will not give you a KeyError.

If you are using lists,

item in list_name

will give either True or False.

Also modify your input to raw_input() so that it considers strings as strings and not as object names.

Try using something like the following:

try:
    dictionary_name[key]
except KeyError:
    #do something
    print "Key Error"

edited May 06 '13 at 23:41

answered May 06 '13 at 23:25

Alagappan Ramu

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I changed it to get rid of the list and just search if the input is in the dictionary – user2356391 May 06 '13 at 23:35
i still get NameError: name 'BIG' is not defined when i input "BIG" for input (and BIG is int he keys of the dictionary) – user2356391 May 06 '13 at 23:36
@user2356391 when you do a normal 'input' in Python, if you enter a value like 'BIG' it is considered to be an object name. Here it is not defined. So as suggested by JoranBeasley change it to raw_input() and your code will work like a charm. – Alagappan Ramu May 06 '13 at 23:40

score -1 · Answer 3 · answered May 06 '13 at 23:30

-1

Maybe I'm misunderstanding something here, but to check if a value is a dictionary key, it's very simple:

'key' in dictionary

which returns True or False.

Additionally, you could even do something like:

mydictionary.get('key', 'Key not in dictionary')

And if the key isn't in the dictionary, you'll get the string "Key not in dictionary", otherwise you'll get the actual value marked by 'key'.

answered May 06 '13 at 23:30

jdotjdot

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There could be a possible bug here if the dictionary contains 'Key not in dictionary' itself as a value. – Alagappan Ramu May 06 '13 at 23:35
This was just an example. And since we're talking about stock tickers, I highly doubt there would be a stock ticker `"Key not in dictionary"` in that dictionary. – jdotjdot May 07 '13 at 02:08

finding key in dict using try except

3 Answers3