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# Python program to print negative numbers in a list

Given a list of numbers, write a Python program to print all negative numbers in the given list.

Example:

```Input: list1 = [12, -7, 5, 64, -14]
Output: -7, -14

Input: list2 = [12, 14, -95, 3]
Output: -95```

Example #1: Print all negative numbers from the given list using for loop Iterate each element in the list using for loop and check if the number is less than 0. If the condition satisfies, then only print the number.

## Python3

 `# Python program to print negative Numbers in a List` `# list of numbers``list1 ``=` `[``11``, ``-``21``, ``0``, ``45``, ``66``, ``-``93``]` `# iterating each number in list``for` `num ``in` `list1:` `    ``# checking condition``    ``if` `num < ``0``:``    ``print``(num, end``=``" "``)`

Output:

`-21 -93 `

Time complexity: O(n)
Auxiliary space: O(n), where n is total number of values in list1.

Example #2: Using while loop

## Python3

 `# Python program to print negative Numbers in a List` `# list of numbers``list1 ``=` `[``-``10``, ``21``, ``-``4``, ``-``45``, ``-``66``, ``93``]``num ``=` `0` `# using while loop``while``(num < ``len``(list1)):` `    ``# checking condition``    ``if` `list1[num] < ``0``:``        ``print``(list1[num], end``=``" "``)` `    ``# increment num``    ``num ``+``=` `1`

Output

`-10 -4 -45 -66 `

Time complexity: O(n), where n is the length of the input list.
Auxiliary space: O(1).

Example #3: Using list comprehension

## Python3

 `# Python program to print negative Numbers in a List` `# list of numbers``list1 ``=` `[``-``10``, ``-``21``, ``-``4``, ``45``, ``-``66``, ``93``]` `# using list comprehension``neg_nos ``=` `[num ``for` `num ``in` `list1 ``if` `num < ``0``]` `print``(``"Negative numbers in the list: "``, ``*``neg_nos)`

Output

`Negative numbers in the list:  -10 -21 -4 -66`

Time complexity: O(n), where n is the number of elements in the input list.
Auxiliary space: O(n), as it creates a new list to store the negative numbers in the input list.

Example #4: Using lambda expressions

## Python3

 `# Python program to print negative Numbers in a List` `# list of numbers``list1 ``=` `[``-``10``, ``21``, ``4``, ``-``45``, ``-``66``, ``93``, ``-``11``]`  `# we can also print negative no's using lambda exp.``neg_nos ``=` `list``(``filter``(``lambda` `x: (x < ``0``), list1))` `print``(``"Negative numbers in the list: "``, ``*``neg_nos)`

Output

`Negative numbers in the list:  -10 -45 -66 -11`

Time complexity: O(n), where n is the number of elements in the list.
Auxiliary space: O(m), where m is the number of negative numbers in the list.

## Python3

 `l``=``[``12``, ``-``7``, ``5``, ``64``, ``-``14``]``print``([a ``for` `j,a ``in` `enumerate``(l) ``if` `a<``0``])`

Output

`[-7, -14]`

## Python3

 `# Python program to print negative Numbers in a List` `# list of numbers``list1 ``=` `[``11``, ``-``21``, ``0``, ``45``, ``66``, ``-``93``]``res ``=` `[]``list2 ``=` `list``(``map``(``str``, list1))``for` `i ``in` `range``(``0``, ``len``(list2)):``    ``if``(list2[i].startswith(``"-"``)):``        ``res.append(``str``(list1[i]))``res ``=` `" "``.join(res)``print``(res)`

Output

`-21 -93`

The time complexity of the given program is O(n), where n is the length of the input list.

The auxiliary space complexity of the program is also O(n), where n is the length of the input list.

## Python3

 `# Python program to print negative Numbers in a List``import` `numpy as np``# list of numbers``list1 ``=` `[``-``10``, ``21``, ``4``, ``-``45``, ``-``66``, ``93``, ``-``11``]`  `# Using numpy to print the negative number``temp ``=` `np.array(list1)``neg_nos ``=` `temp[temp <``=` `0``]` `print``(``"Negative numbers in the list: "``, ``*``neg_nos)`

Output:

`Negative numbers in the list:  -10 -45 -66 -11`

Time Complexity: O(n)
Auxiliary Space: O(n)

## Python3

 `#Recursive function to check current element negative or not``def` `PrintNegative(itr,list1):``  ``if` `itr ``=``=` `len``(list1): ``#base condition``    ``return``  ``if` `list1[itr] < ``0``: ``#check negative number or not``    ``print``( list1[itr],end ``=` `" "``)``  ``PrintNegative(itr``+``1``,list1) ``#recursive function call``  ` `list1 ``=` `[``-``1``,``8``,``9``,``-``5``,``7``]``PrintNegative(``0``,list1)`

Output

`-1 -5 `

Method: Using numpy.array() and numpy.where()

## note: install numpy module using command “pip install numpy”

Algorithm:

Convert the input list to a numpy array using numpy.array() method.
Use numpy.where() method to find all the negative numbers in the array.
Print the negative numbers.

## Python3

 `import` `numpy as np` `# list of numbers``list1 ``=` `[``12``, ``-``7``, ``5``, ``64``, ``-``14``]` `# converting list to numpy array``arr1 ``=` `np.array(list1)` `# finding negative numbers in the array``neg_nums ``=` `arr1[np.where(arr1 < ``0``)]` `# printing negative numbers``print``(``"Negative numbers in the list: "``, ``*``neg_nums)`

Output:

`Negative numbers in the list:  -7 -14`

Time complexity: O(n), where n is the length of the input list.

Auxiliary space: O(n), as we are creating a numpy array to store the input list and another numpy array to store the negative numbers.

### Method : Using functools.reduce

Algorithm:

• Initialize the test list.
• Use reduce function with the lambda function which adds a negative element to the list.
• Print list.

## Python3

 `# Python program to print negative Numbers in a List``from` `functools ``import` `reduce` `# list of numbers``list1 ``=` `[``-``10``, ``-``21``, ``-``4``, ``45``, ``-``66``, ``93``]` `# using reduce method``neg_nos ``=` `reduce``(``lambda` `a, b : a ``+` `[ b ] ``if` `b < ``0` `else` `a ,list1, [])` `print``(``"Negative numbers in the list: "``, ``*``neg_nos)`

Output

```Negative numbers in the list:  -10 -21 -4 -66
```

Time complexity: O(N), where N is the length of the test list.

Auxiliary space: O(M), where M is length of the negative number list.