Contents
- Introduction
- Create 1D Numpy Array using array() function
- Create 1D Numpy Array using arange() function
- Create 1D Numpy Array using linspace() function
- Summary
One dimensional array contains elements only in one dimension. In other words, the shape of the numpy array should contain only one value in the tuple.
To create a one dimensional array in Numpy, you can use either of the array(), arange() or linspace() numpy functions.
Create 1D Numpy Array using array() function
Numpy array() functions takes a list of elements as argument and returns a one-dimensional array.
In this example, we will import numpy library and use array() function to crate a one dimensional numpy array.
Python Program
import numpy as np #create numpy array a = np.array([5, 8, 12]) print(a)Run
Output
[ 5, 8, 12]Create 1D Numpy Array using arange() function
Numpy arange() function takes start, end of a range and the interval as arguments and returns a one-dimensional array.
Run
In this example, we will import numpy library and use arange() function to crate a one dimensional numpy array.
Python Program
import numpy as np #create numpy array a = np.arange(5, 14, 2) print(a)Run
Output
[ 5, 7, 9, 11, 13]Array starts with 5 and continues till 14 in the interval of 2.
Create 1D Numpy Array using linspace() function
Numpy linspace() functions takes start, end and the number of elements to be created as arguments and creates a one-dimensional array.
In this example, we will import numpy library and use linspace() function to crate a one dimensional numpy array.
Python Program
import numpy as np #create numpy array a = np.linspace(5, 25, 4) print(a)Run
Output
[ 5. 11.66666667 18.33333333 25. ]Summary
In this tutorial of Python Examples, we created one-dimensional numpy array using different built-in functions.
Two dimensional array is an array within an array. It is an array of arrays. In this type of array the position of an data element is referred by two indices instead of one. So it represents a table with rows an dcolumns of data.
In the below example of a two dimensional array, observer that each array element itself is also an array.
Consider the example of recording temperatures 4 times a day, every day. Some times the recording instrument may be faulty and we fail to record data. Such data for 4 days can be presented as a two dimensional array as below.
Day 1 - 11 12 5 2 Day 2 - 15 6 10 Day 3 - 10 8 12 5 Day 4 - 12 15 8 6The above data can be represented as a two dimensional array as below.
T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]]Accessing Values
The data elements in two dimesnional arrays can be accessed using two indices. One index referring to the main or parent array and another index referring to the position of the data element in the inner array.If we mention only one index then the entire inner array is printed for that index position.
Example
The example below illustrates how it works.
from array import * T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]] print(T[0]) print(T[1][2])Output
When the above code is executed, it produces the following result −
To print out the entire two dimensional array we can use python for loop as shown below. We use end of line to print out the values in different rows.
Example
from array import * T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]] for r in T: for c in r: print(c,end = " ") print()Output
When the above code is executed, it produces the following result −
11 12 5 2 15 6 10 10 8 12 5 12 15 8 6Inserting Values
We can insert new data elements at specific position by using the insert() method and specifying the index.
Example
In the below example a new data element is inserted at index position 2.
from array import * T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]] T.insert(2, [0,5,11,13,6]) for r in T: for c in r: print(c,end = " ") print()Output
When the above code is executed, it produces the following result −
11 12 5 2 15 6 10 0 5 11 13 6 10 8 12 5 12 15 8 6Updating Values
We can update the entire inner array or some specific data elements of the inner array by reassigning the values using the array index.
Example
from array import * T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]] T[2] = [11,9] T[0][3] = 7 for r in T: for c in r: print(c,end = " ") print()Output
When the above code is executed, it produces the following result −
11 12 5 7 15 6 10 11 9 12 15 8 6Deleting the Values
We can delete the entire inner array or some specific data elements of the inner array by reassigning the values using the del() method with index. But in case you need to remove specific data elements in one of the inner arrays, then use the update process described above.
Example
from array import * T = [[11, 12, 5, 2], [15, 6,10], [10, 8, 12, 5], [12,15,8,6]] del T[3] for r in T: for c in r: print(c,end = " ") print()Output
When the above code is executed, it produces the following result −
11 12 5 2 15 6 10 10 8 12 5