which is the best approach to perform for loop?-CodePudding

I have a list of lists and inside every list, I have to check if the second element is "daemon", so I wrote a code to that like this:

### code 1
def chech_for_count(my_list: list):
    counter_of = 0
    for item in my_list:
       if item[1].lower() == "daemon":
            counter_of  = 1
    return counter_of

and the task was achieved well but came to my mind I could also make that done using list comprehension which I think it's more pythonic.

### code 2
def chech_for_count(my_list: list):
    return len([item for item in my_list if item[1].lower() == "daemon"])

also, the code did what must be done successfully, my question is which one uses less memory and time?

I did a little test with time.time() and the results varied from one test to another like below:

| Test number|Using list comprehension|Using normal for-loop  |
|------------|------------------------|-----------------------|
| First      | 0.2046670913696289     | 0.18691778182983398   |
| Second     | 0.11920547485351562    | 0.20410394668579102   |
| Third      | 0.09914922714233398    | 0.1051473617553711    |
| Forth      | 0.10482406616210938    | 0.1894378662109375    |
| Sum        | 0.52784585952758788    | 0.6856069564819336    |

The reason behind my question because I doubt if these numbers are real because I think some tests were slower because of CPU usage or something related to the hardware if not, based on these results can we say list comprehension has a better performance?

CodePudding user response：

As stated in the comments you can use sum():

my_list = [[1, "xxx"], [2, "deamon"], [3, "deamon"]]

print(sum(l[1] == "deamon" for l in my_list))

Prints:

EDIT: Case-insensitive version:

my_list = [[1, "xxx"], [2, "DEAMON"], [3, "deamon"]]

print(sum(l[1].lower() == "deamon" for l in my_list))

Prints: