## # 5 Data Type in Python Language

Python programmers often have problem with their script. Their script cannot run well, often because of the incorrect data type. Some of the different data types can not work in one operation and python give error result.

In this article, we will show 5 data type in python. Python has five standard Data Types.

The Python data types are: numbers, strings, list, tuple, and dictionary.

This is something that every programmer need to know. It help us to prevent error and make dream program into reality.

## Numbers

“The most used number data type is integer and floating. But that is not the only number data type in python. Python has another number data type. There is complex, decimals and fractions.

### Integer

Integer is the whole number without fractional number. It includes positive, negative and zero number. But it does not include 1.5, because that is a fractional number. 50% is not an integer because it is a fractional number. Example of integer is -60, 31, 0, 50 38. and so on.
If we assign integer number to a variable, python automatically defines its number and variable as an integer.
In Python programming language, declaration data as number is simple. Write a variable and assign a number without punctuation.
This is an example. Var1 = 23. This is make var1 as number integer data type. Yo can check the type of variable by writing “type(var)” in python.

``````>>> var = 34
>>> type(var)
<type 'int'>``````

### Float Point Number

Float point number is fractional number or decimal number. The fractional part or decimal part of a non‐negative real number is the excess beyond that number’s integer part. For example 0.1, 5.1.
In python, to define that some variable as float type, we just assign float point number to a variable. For example, we have variable C and data float point, 1.3.

``````>>> c= 1.3 # dot in this number is sign of decimal number after dot.
>>> type(c)
<type 'float'>``````

It is possible in python to make mathematic operatation between float and integer. For example

``````>>> c= 1.3
>>> type(c)
<type 'float'>
>>> d = 29
>>> type(d)
<type 'int'>
>>> w = c+d
>>> w
30.3
>>> type(w)
<type 'float'>       ``````

Python support operand type(s) for float and integer.

### Complex Number

Complex number is a combination of real number and imaginative number. The syntax of complex number is , + j. We has to add “j” to imaginary part. Example

``````>>> 3+6j
(3+6j)"``````

## Strings

strings are sequences of alphabet, text, or number data. It is character data. Number as character data different than gives integer. If we assign number as character data, we can not make mathematic operation correctly.

To make python understand, that some data is strings is by add quote or double quote befor and after data. The data is include

This is example number as character data.

``````>>> x = '9'  #
>>> type(x)
<type 'str'>
>>> x *5
'99999'``````

The example show that ‘9’ * 5 (‘9’ multiply 5) is not 45, but ‘99999’. Because, the ‘9’ is not integer, but string.

If the between string and integer is allowed, python cannot do the addition for them. It is example. Python give error message.

``````>>> x = '8'
>>> x*4
'8888'
>>> x +5
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: cannot concatenate 'str' and 'int' objects
>>>``````

## List

A variable can have more than one data or lists. Python have 3 distinct lists. There are: list, tuple, and dictionary. In this section we talk about list.

List is a collection of values. It is series of values. Data type of values can be number or strings. List variables are declared by using brackets  “[” and “]” following the variable name. See distinct of {}, (), and [] carefully.

Tuple is also collection of values. Unique feature of list compare to tuple is mutable. We change the member of list easily.

``````your_list = [2,3,4,5,6]
my_list = ["we', "are", "champion"]
empty_list = []``````

Python give index of every member of list. The index is start with 0. There are 0,1,2,3 and so on. So we can also retrieve the list by its index number. For example.

``````>>> ere = ["yes", 90, "wow"]
>>> ere[0]
'yes'
>>> ere[2]
'wow'``````

List can be member of another list.

``````>>> ere = ["yes", 90, "wow"]
>>> newlist = [ere, [3,5,"5"]]
>>> newlist
[['yes', 90, 'wow'], [3, 5, '5']]
>>>``````

We can retrieve list in the list by two bracket square.

``````>>> newlist
[['yes', 90, 'wow'], [3, 5, '5']]
>>> newlist[0][1]
90
>>>``````

## Tuple

Tuple is also collection of value. Different than list data type, tuple data type immutable. We can not change its member easily.

It is simple to create a tuple. We can type colletion of value within parenthesis ().

``````>>> mytuple=(1,2,"three")
>>> type(mytuple)
<type 'tuple'>
>>>
``````

## Dictionary

Dictionary is also a collection of value. But different than list and tuple, dictionary, the values of dictionary are pair of key and value. Imagine about an english german dictionary. The list have pair of english word and its meaning in germany language.

`` eng2g = {"one": "eins", "two": "zwei", "three": "drei"}``

To declare a variable as dictionary is simple. If list have bracket square [], tuple have parenthesis (), dictionary have {}. The pair of value have :

``````>>> gg ={}
>>> type(gg)
<type 'dict'>
>>>``````

## #4 Python Glossary: Operator

Operators in python is symbol that can perform value or variable. Operator can execute math, logic, assignment, comparison et cetera operation and give result. Without operator, variable only, python is only store value. But, python have operators so it can make calculate and imitate human mind.

There are various operators in python.

• Arithmetic operator
• comparison/ relational operator
• assignment operator
• logical operator
• membership operator
• Identity operator
• presedence operator

## Arithmetic Operator

Arithmetic operator takes two value or variable then performs a calculation on them. The math operation is for example : addition (+), subtraction (-), multiplication (*) , division (/), %modulus , exponentiation(**). There are basic mathematical operations.

``````>>> #this is addition or plus
>>> 3+5
8``````
``````>>> #this is substraction or minus
>>> 10 - 3
7``````
``````>>> #this is multiply two operand (value or variable)  either side of the operator
>>> 4 * 5
20``````
``````>>> #division divide first operand by second operand
>>> 10 / 2
5``````
``````>>> # modulus divides and returns the value of the remainder.
>>> 10%3
1
``````

## Comparison/ Relational Operator

Comparison/ relational operators compare the values on two sides of the value or variable. For example, 4 < 2 (output = False). After we write a comparison between value /variable/operand, then Python program in run mode will tell whether an operand is greater than the other, lesser, equal, or a combination of those. Various comparison operators are ( ==, != , <>, >,<=, etc)

``````>>> #Equal to (==) check whether first operand equal to the second
>>> 5 == 5
True
>>> x = 10
>>> x == 11
False``````
``````>>> # Not equal to (!=) will check whether first is not equal to the second
>>> 3 != 1
True
>>> 5 != 5
False``````

## Assignment Operator

Assignment operators in Python assign the value to a variable. Assign variable that already has value to a variable is allowed. But we can not assign a variable that has no value to a variable. There are several assignment operators used in Python (=, +=, – = , *=, /= , etc.)

## Logical Operator

Logical operators consist 3 operator: or, and, not. That are used for combined conditional statements are true or false. The ‘and’ operator return to True only if two side are True. The ‘or’ operator return to True if one or two side are True. The ‘not’ for True is False. The ‘not’ for False is True.

## Membership Operator

Membership operator check whether some value is membership of lists. There are two membership operator in Python: ‘in’ and ‘not in’

## Identity Operator

Identity operator check whether two object is same. There are two identity operator. There are ‘is’ and ‘not is’.

## Precedence operator

Precedence operator avoids ambiguity. It determines which operators need to be evaluated first. Precedence operator consists of parenthesis or (). Then multiplication has a higher precedence than addition.

## #3 Python Glossary : Variable

We have not to find meaning every word in python code. Some of them is user-defined name variable. So their word is as the programmer like.

If we write or read python script, variables often appear. A variable is a container that represents data that we know or we decide it later. in algebra, a variable is a symbol for a number we don’t know yet. It is usually a letter like x or y. In Python, the variable is represented numbers, word, and lists that we already assign or we will assign later.

Compare to spreadsheet like excel, python variable is like cell. Cell is empty container that we can decide value later. Python variable is a reserved memory location. Variable is place that we can store values.

Form of variable in python is:

• user-defined alphabet or word. The programmer defines a variable name, so find reference of the word is not necessary. So, a programmer can define a variable: var1, dido, doli, bubu, this_is_variable, and so on.
• a variable name has no spaces.
• start with a letter or underscore. We can not write a variable that starts with numbers. So, this example that is allowed: yoyo1, y4_ya, y1yi, et cetera. This is the example that not allowed: 1ya, 2yoyo et cetera.
• consist one or more under case letter, underscore and number. We can not put a number in the first alphabet, but we can put it in a second or more position. For example my_variable, energy_var1, and so on.
• Some of the words are python word that has specifics function. So we can not use 33 python keywords as a variable. They have another use in python. Python 33 keywords is : False. class, finally, is, return, None, continue, for, lambda, try, True, def, from, nonlocal, while, and, del, global, not, with, as, elif, if, or, yield, assert, else, import, pass, break, except, in, raise.
• we can assign variable by using “=”. For example my_variable = 10
• a variable is unique. We can not have two variables that have the same name. Python read it as same variable. Python read last statement as a valid value of the variable. You can see the example below.
``````>>> my_variable = 10
>>> print my_variable
10
>>> my_variable = 11
>>> print my_variable
11``````
• A variable can contain number, text (string), or list (set of data).
• To assign text to a variable, we have to give quotation mark before and after text.
• We can assign variable with set of data list. For example, we have a variable that has named my_book. It can contain a set of data.
``````>>> my_book =['python for beginner', 'dive to python', 'business']
>>> my_text_variable = 'it is text'``````

## #2 First Important Lesson for Python Beginners

Sometimes some of the people have to learn Python programming language in a limited time. Usually, it has to learn because the job challenges them to create python programming. So this article talk about how to start learn and practice python. What issue that we need to know first?
The topic is important because we need to make a good job about python at a limited time.

I argue that important point for beginners to know about python is about program installation, workflow, and the glossary.

Install python program and the related program is important to know. So we can run the program and do the jobs. Workflow of programming is also important, so we can finish and give benefit, even if we create a simple program. Python Glossary is also important to know, so we can write and read python language that computer can obey.

## Python and IDE Program Installation

First point. To start to learn Python, we need to know how to install python and related program. Different from another program that it is better to select the newest version of the program, python is not like that. That is because python 2x (Python version that begins with 2) sometimes not compatible with python 3x.

If we have a script that is written in Python 2, we cannot run it by python 3. However, if we want to create scripts from scratch, from blank, it is better to choose python 3, because python foundation will develop python 3. Their support for Python 2 will stop at 2020. Related program to write python code is Integrated Development Environment (IDE) for python. IDE is text editor to write python that has featured that support us to write correctly.

I will show you how to install python and IDE python text editor.

Python have features: program that run the code and IDE text Editor. If you want to try another alternative of text editor for python programming, it is a list of that.

• pycharm
• sublime text 3

## Workflow of Programming

To begin start python programming, we need to know about the workflow of programming. Workflow programming is simple, but if we do not know, we confuse.

Workflow of programming is two steps. First is writing code in text editor IDE. Second, run program in python. Python also have command prompt, it is place to try or learn program. Python command prompt did not save your code, so don’t write your code here. To access IDE, open your chosen IDE program. If you want to run program, usually IDE have feature to run program.

To practice about programming, we can start to create simple program.

Open text editor IDE, like Python IDLE (Python GUI), Sublime Text, Pycharm, Notepad++ .

That is picture of Python IDLE in windows environment. Click IDLE then write as below.

``print (‘Hello world’)``

Then save code file, with .py extension. Then run the code. To run the code, click run menu on the top, then run module or F5 in windows. then you will see program in run mode.

That is work flow of python programming.

• Open text editor or IDE (Integrated Development Environment)
• Write the code
• save file to be py extension
• Run code

## Python Glossary

If we know about Python Glossary and punctuation, we can read and write more easily. Of course, some code is long and complex, so we sometimes do not understand. But by know Python glossary, we have step forward to read complex code.

Compare to human language as English, Greek language and so on, Python have different language. Human language has words, sentence, and composition. Python has words, sentence and composition, but it is different. Guido von Rossum create Python language, so it can be read by computer and human. Python is language so human can instruct and program a computer.

Program is instruction or set of instruction that computer can understand and run.

Component of instructions are

• variable
• operator (conditional, logic, arithmetic),
• data type,
• lists,
• loops.
• Class