### Question :

If I want the maximum value in a list, I can just write `max(List)`

, but what if I also need the index of the maximum value?

I can write something like this:

```
maximum=0
for i,value in enumerate(List):
if value>maximum:
maximum=value
index=i
```

But it looks tedious to me.

And if I write:

```
List.index(max(List))
```

Then it will iterate the list twice.

Is there a better way?

##
Answer #1:

There are many options, for example:

```
import operator
index, value = max(enumerate(my_list), key=operator.itemgetter(1))
```

##
Answer #2:

I think the accepted answer is great, but why don’t you do it explicitly? I feel more people would understand your code, and that is in agreement with PEP 8:

```
max_value = max(my_list)
max_index = my_list.index(max_value)
```

This method is also about three times faster than the accepted answer:

```
import random
from datetime import datetime
import operator
def explicit(l):
max_val = max(l)
max_idx = l.index(max_val)
return max_idx, max_val
def implicit(l):
max_idx, max_val = max(enumerate(l), key=operator.itemgetter(1))
return max_idx, max_val
if __name__ == "__main__":
from timeit import Timer
t = Timer("explicit(l)", "from __main__ import explicit, implicit; "
"import random; import operator;"
"l = [random.random() for _ in xrange(100)]")
print "Explicit: %.2f usec/pass" % (1000000 * t.timeit(number=100000)/100000)
t = Timer("implicit(l)", "from __main__ import explicit, implicit; "
"import random; import operator;"
"l = [random.random() for _ in xrange(100)]")
print "Implicit: %.2f usec/pass" % (1000000 * t.timeit(number=100000)/100000)
```

Results as they run in my computer:

```
Explicit: 8.07 usec/pass
Implicit: 22.86 usec/pass
```

Other set:

```
Explicit: 6.80 usec/pass
Implicit: 19.01 usec/pass
```

##
Answer #3:

This answer is 33 times faster than @Escualo assuming that the list is very large, and assuming that it’s already an np.array(). I had to turn down the number of test runs because the test is looking at 10000000 elements not just 100.

```
import random
from datetime import datetime
import operator
import numpy as np
def explicit(l):
max_val = max(l)
max_idx = l.index(max_val)
return max_idx, max_val
def implicit(l):
max_idx, max_val = max(enumerate(l), key=operator.itemgetter(1))
return max_idx, max_val
def npmax(l):
max_idx = np.argmax(l)
max_val = l[max_idx]
return (max_idx, max_val)
if __name__ == "__main__":
from timeit import Timer
t = Timer("npmax(l)", "from __main__ import explicit, implicit, npmax; "
"import random; import operator; import numpy as np;"
"l = np.array([random.random() for _ in xrange(10000000)])")
print "Npmax: %.2f msec/pass" % (1000 * t.timeit(number=10)/10 )
t = Timer("explicit(l)", "from __main__ import explicit, implicit; "
"import random; import operator;"
"l = [random.random() for _ in xrange(10000000)]")
print "Explicit: %.2f msec/pass" % (1000 * t.timeit(number=10)/10 )
t = Timer("implicit(l)", "from __main__ import explicit, implicit; "
"import random; import operator;"
"l = [random.random() for _ in xrange(10000000)]")
print "Implicit: %.2f msec/pass" % (1000 * t.timeit(number=10)/10 )
```

Results on my computer:

```
Npmax: 8.78 msec/pass
Explicit: 290.01 msec/pass
Implicit: 790.27 msec/pass
```

##
Answer #4:

With Python’s built-in library, it’s pretty easy:

```
a = [2, 9, -10, 5, 18, 9]
max(xrange(len(a)), key = lambda x: a[x])
```

This tells `max`

to find the largest number in the list `[0, 1, 2, ..., len(a)]`

, using the custom function `lambda x: a[x]`

, which says that `0`

is actually `2`

, `1`

is actually `9`

, etc.

##
Answer #5:

I would suggest a very simple way:

```
import numpy as np
l = [10, 22, 8, 8, 11]
print(np.argmax(l))
print(np.argmin(l))
```

Hope it helps.

##
Answer #6:

```
max([(v,i) for i,v in enumerate(my_list)])
```

##
Answer #7:

```
max([(value,index) for index,value in enumerate(your_list)]) #if maximum value is present more than once in your list then this will return index of the last occurrence
```

If maximum value in present more than once and you want to get all indices,

```
max_value = max(your_list)
maxIndexList = [index for index,value in enumerate(your_list) if value==max(your_list)]
```

##
Answer #8:

Maybe you need a sorted list anyway?

Try this:

```
your_list = [13, 352, 2553, 0.5, 89, 0.4]
sorted_list = sorted(your_list)
index_of_higher_value = your_list.index(sorted_list[-1])
```