In this tutorial, we will look at how to check if all the elements in a list are positive (greater than 0
) or not in Python with the help of some examples.
How to check if all the list items are positive?
You can use the Python built-in all()
function to check if all the elements in a list are positive or not by comparing each value in the list with 0
.
The all()
function takes in an iterable as an argument and returns True
if all the values in the iterable are truthy (represent True
in a boolean context).
So, to check if all the values in a given list are positive or not, use the all()
function to check if all the values are greater than 0
. The following is the syntax –
# check if all the list values are positive all(val > 0 for val in ls)
It returns True
if all the values in the list are greater than 0
.
Note that there are other methods as well that you can use to check if all list values are positive or not. For example –
- Iterate through the list and keep a count of values that are greater than
0
. If this count is the same as the length of the list, you can say that all values are positive.
Examples
Let’s now look at some examples of using the above methods. First, we will create a few lists that we’ll use to demonstrate the methods.
# list with all positive values ls1 = [1, 2, 3, 4, 5, 5] # list with positive, negative and zero values ls2 = [0, 1, 2, 3, -4, 5, -5] # empty list ls3 = [] # display the lists print(ls1) print(ls2) print(ls3)
Output:
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[1, 2, 3, 4, 5, 5] [0, 1, 2, 3, -4, 5, -5] []
Here, we created three lists – ls1
, ls2
, and ls3
. The list ls1
contains only positive values as its elements. The list ls2
has repeated values but not all values are greater than zero and the list ls3
is empty (it does not contain any elements).
Example 1 – Check if all the list elements are positive using all()
The idea here is to use the all()
function to check if each list element is positive (greater than 0
).
You can use a list comprehension to create a list of boolean values – whether a list element is greater than 0
or not and then pass this resulting list as an argument to the all()
function.
Let’s apply this to the lists ls1
and ls2
created above.
# check if all list values are positive print(all([val > 0 for val in ls1])) print(all([val > 0 for val in ls2]))
Output:
True False
We get True
for ls1
and False
for ls2
.
If you apply this method to an empty list, you’ll get True
as the output.
all([val > 0 for val in ls3])
Output:
True
Note that the all()
takes an iterable as an argument, you can directly use an iterator (without using a list comprehension).
# check if all list values are positive print(all(val > 0 for val in ls1)) print(all(val > 0 for val in ls2)) print(all(val > 0 for val in ls3))
Output:
True False True
We get the same results as above.
Example 2 – Check if all list elements are positive using a for loop
The idea, here, is to iterate through the list and keep a count of positive values in the list. If the resulting count is the same as the length of the list, we can say that all the values in the list are positive.
def all_list_elements_positive(ls): count = 0 for val in ls: if val > 0: count += 1 return count == len(ls) # check if all list values are positive print(all_list_elements_positive(ls1)) print(all_list_elements_positive(ls2)) print(all_list_elements_positive(ls3))
Output:
True False True
We get True
for ls1
and False
for ls2
. Note that here we get True
for an empty list.
Summary
In this tutorial, we looked at some different methods to check if all the values in a list are positive or not. The following are the different methods covered –
- Use the Python built-in
all()
function to check if each list element is greater than zero. - Iterate through the list elements and track the count of values that are greater than zero and then compare this count with the length of the list.
You might also be interested in –
- Python – Check If All Elements in List are Strings
- Python – Check If All Elements in List are Integers
- Python – Check If All Elements in List are None
- Python – Check If All Elements in List are Zero
- Python – Check If All Elements in a List are Equal
- Python – Check If All Elements in a List are Unique
- Check If a List Contains Only Numbers in Python
- Python – Check List Contains All Elements Of Another List
- Python – Check if an element is in a list
- Python – Check If List Is Sorted Or Not
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