Confuse with output in python

Question

I want to find the maximum temperature in a set of data and print the output as "The hottest temperature was x in y" where x and y is temperature and city respectively. I have a code like this:

data = [['Sheffield', '41.2', '35.5', '41.1'],
       ['Lancaster', '31.3', '40.2', '37.9'],
       ['Southampton', '34.8', '33.9', '32',],
       ['Manchester', '41.9', '41.5', '44.2'],
       ['Bristol', '42.1', '37.1', '42.2']]

hot = []
for row in data:
    for item in row:
        if item == max(row[1:]):
           hot.append(item)

    if max(hot) in row:
       print "The hottest temperature was {0} in {1}.".format(max(hot),row[0])

The outputs that were produced:

The hottest temperature was 41.2 in Sheffield.
The hottest temperature was 44.2 in Manchester.

Now I am confused with the outputs. I want to print only one line of output which is supposed to be "The hottest temperature was 44.2 in Manchester." since 44.2 is the maximum temperature in the data. Why did "The hottest temperature was 41.2 in Sheffield." is printed too? Where did I get it wrong?

chepner · Accepted Answer · 2013-04-30 13:28:26Z

1

You check if the maximum value of hot is in row for each row, rather than checking once after all the rows have been processed.

Try this:

hot = []
for row in data:
    for item in row:
        if item == max(row[1:]):
           hot.append(item)

    if max(hot) in row:
       max_row = row

print "The hottest temperature was {0} in {1}.".format(max(hot),max_row[0])

As an aside, you are storing all your temperatures as strings, not floats. You could get an odd result if there is a much wider spread of temperatures ('5' > '35.3' is true, for example).

answered Apr 30, 2013 at 13:28

chepner

538k77 gold badges594 silver badges746 bronze badges

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

1 Comment

Fynn Mahoney Over a year ago

Thank you for your solution. Now I know where I got it wrong.

Daniel Roseman · Accepted Answer · 2013-04-30 13:27:55Z

1

You're building up the list as you iterate, and the max is operating on the list as you have it so far. When you get to Sheffield, it's the hottest you've seen so far, so it prints. But it can't know that Manchester is even hotter, as it hasn't seen it yet.

The quickest way to fix this would be to do two loops: one to build up the list, then a second to find the hottest.

(And, 44.2 in Manchester? In your dreams.)

answered Apr 30, 2013 at 13:27

Daniel Roseman

602k68 gold badges910 silver badges923 bronze badges

Comments

PBD · Accepted Answer · 2013-04-30 13:38:03Z

1

data = [['Sheffield', '41.2', '35.5', '41.1'],
   ['Lancaster', '31.3', '40.2', '37.9'],
   ['Southampton', '34.8', '33.9', '32',],
   ['Manchester', '41.9', '41.5', '44.2'],
   ['Bristol', '42.1', '37.1', '42.2']]

hot = []
for row in data:
    for item in row:
        if item == max(row[1:]):
            hot.append(item) 

for row in data:
    if max(hot) in row:
         print "The hottest temperature was {0} in {1}.".format(max(hot),row[0])

Try the above one this should work as you expected...

answered Apr 30, 2013 at 13:38

PBD

1112 silver badges5 bronze badges

2 Comments

whatyouhide Over a year ago

Code inside answers on Stack Overflow should be explained, not just pasted as is, in order to make the user who asked the question understand your answer.

PBD Over a year ago

@whatyouhide : Thanks for your suggestion, i started posting the answers quite recently from now onwards i strictly follow the your suggestion.

Ahmet DAL · Accepted Answer · 2013-04-30 13:37:24Z

0

First of all I wanna say this is not efficient way to do what you want. But if you wanna know why you are getting this result, I'll explain it for you;

You are creating hot list for every list element of data and finding max value in hot list. In first loop it is 41.2 and it is really inside of the first row. So, it prints it normally.
Until loop is for third list element of data , there is no max value than 41.2 and there is no printing.
When the loops is for third list element in data, the max value is 44.2 and it is printed and there will be no max value than this after now and there will be no printing.

answered Apr 30, 2013 at 13:37

Ahmet DAL

4,74210 gold badges52 silver badges75 bronze badges

Comments

fog · Accepted Answer · 2013-04-30 20:12:39Z

0

A two line, quite "pythonic" way of doing it:

hot = sorted([(max(x[1:]), x[0]) for x in data], key=lambda x: x[0])[-1]
print "The hottest temperature was {0} in {1}.".format(*hot)

answered Apr 30, 2013 at 20:12

fog

3,4411 gold badge27 silver badges32 bronze badges

Collectives™ on Stack Overflow

Confuse with output in python

5 Answers 5

1 Comment

Comments

2 Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

1 Comment

Comments

2 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related