python. finding largest integer in string - string

Question

Write the function largestNumber(text) that takes a string of text and returns the largest int value that occurs within that text, or None if no such value occurs.
For example:
largestNumber("I saw 3 dogs, 17 cats, and 14 cows!")
returns 17 (the int value 17, not the string "17").
and
largestNumber("One person ate two hot dogs!")
returns None (the value None, not the string "None").
I tried using isdigit function to separate out integer but how can I compare string?

Answer 1

You can try using a regex, and then max and map functions:
result = [e for e in re.split("[^0-9]", "I saw 3 dogs, 17 cats, and 14 cows!") if e != '']
# list 'result' elements are strings: ['3', '17', '14'], so we use map(int, list) to get integers
print max(map(int, result))

Answer 2

You could also do
def largestNumber(in_str):
l=[int(x) for x in in_str.split() if x.isdigit()]
return max(l) if l else None
First you split in_str based on space () with split() to get a list.
The 'numbers' in this list are identified using isdigit() and converted to integers using int().
These numbers are stored in l as a list.
The expression
max(l) if l else None
will give maximum value in l if l is not empty and otherwise None.
print(largestNumber("I saw 3 dogs, 17 cats, and 14 cows!"))
gives
17
and
print(largestNumber("One person ate two hot dogs!"))
gives
None

Answer 3

Just Another solution:
def findLargestNumber(text):
ls = list()
for w in text.split():
try:
ls.append(int(w))
except:
pass
try:
return max(ls)
except:
return None
print findLargestNumber('I saw 3 dogs, 17 cats, and 14 cows!')
print findLargestNumber('I saw ')
Output:
17
None

Answer 4

def findLargestNumber(text):
front = -1
li = []
for i in range(len(text)):
if front == -1:
if text[i].isdigit():
front = i
else:
continue
else:
if text[i].isdigit():
continue
else:
li.append(int(text[front:i+1]))
front = -1
return max(li)
print findLargestNumber('I saw 3 dogs, 17 cats, and 14 cows!')

Answer 5

import re
def extractmax(str1):
nums=re.findall("\d+",str1)
return max(nums)
\d+ is used to look for a decimal or number with length greater than one, it is appended into the array nums finally maximum value from nums if generated.

Answer 6

The following worked for me, and it works great!
Increment number in the string and then print out the max number in string
import re
import re
Increase number in string
name = "name 1"
number = re.search(r'\d+', str(name))
if number:
rx = r'(?<!\d){}(?!\d)'.format(number.group())
prefix = re.sub(rx, lambda x: str(int(x.group()) + 1), name)
print(prefix)
Instead of just printing this row directly "re.sub(rx, lambda x: str(int(x.group()) + 1), name)"
Store it in a variable, in my case prefix
That's because you will get the updated value in the string and not the original
Store incremented variable "name" into a list
li = [int(prefix[5:])]
print("Largest name", max(li))
Keep in mind that index 5 is where the number is starting, you may need to adjust it depending on the string length
You can try to make 2 variables to see if the max method is working properly