Python – Check If All Elements in List are Positive

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:

📚 Data Science Programs By Skill Level

Introductory

Intermediate ⭐⭐⭐

🔎 Find Data Science Programs 👨‍💻 111,889 already enrolled

Disclaimer: Data Science Parichay is reader supported. When you purchase a course through a link on this site, we may earn a small commission at no additional cost to you. Earned commissions help support this website and its team of writers.

```[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 –