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Python – Iterative Pair Pattern
• Last Updated : 23 Jul, 2020

Sometimes, while working with Python, we can have problem in which we need to perform the pattern construction or iterative pair string in which second element keeps increasing. This kind of problem can have application in day-day programming and school programming. Lets discuss certain ways in which this task can be performed.
Method #1 : Using loop
This is brute force way in which this task can be performed. In this, we manually check for the second element and perform an increment on each iteration and store.

## Python3

 `# Python3 code to demonstrate working of``# Iterative Pair Pattern``# Using loop` `# initializing 1st element``frst_ele ``=` `'G'` `# initializing 2nd element``secnd_ele ``=` `'*'` `# initializing N``N ``=` `4` `# Iterative Pair Pattern``# Using loop``res ``=` `frst_ele ``+` `secnd_ele``for` `idx ``in` `range``(``1``, N):``    ``res ``+``=` `frst_ele ``+` `secnd_ele ``*` `(idx ``+` `1``)` `# printing result``print``(``"The constructed pattern is : "` `+` `str``(res))`
Output :
```The constructed pattern is : G*G**G***G****

```

Method #2 : Using join() + generator expression
The combination of above methods can be used to perform this task. In this, we perform the task of increment and pattern construction in one liner logic in generator expression.

## Python3

 `# Python3 code to demonstrate working of``# Iterative Pair Pattern``# Using join() + generator expression` `# initializing 1st element``frst_ele ``=` `'G'` `# initializing 2nd element``secnd_ele ``=` `'*'` `# initializing N``N ``=` `4` `# Iterative Pair Pattern``# Using join() + generator expression``res ``=` `frst_ele.join(secnd_ele ``*` `idx ``for` `idx ``in` `range``(N ``+` `1``))` `# printing result``print``(``"The constructed pattern is : "` `+` `str``(res))`
Output :
```The constructed pattern is : G*G**G***G****

```

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