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## 10 Questions, 10 Minutes – SQL/R/Python – 3/100

1.What will the following code output?

`>>> word=’abcdefghij’ >>> word[:3]+word[3:] `

The output is ‘abcdefghij’. The first slice gives us ‘abc’, the next gives us ‘defghij’.

2.How will you convert a list into a string?

We will use the join() method for this.

`>>> nums=['one','two','three','four','five','six','seven'] >>> s=' '.join(nums) >>> s   `

‘one two three four five six seven’

3. How will you remove a duplicate element from a list?

We can turn it into a set to do that.

```>>> list=[1,2,1,3,4,2]
>>> set(list)
{1, 2, 3, 4} ```

4. Explain the //, %, and ** operators in Python.

The // operator performs floor division. It will return the integer part of the result on division.

`>>> 7//2 3 `

Normal division would return 3.5 here.

Similarly, ** performs exponentiation. a**b returns the value of a raised to the power b.

`>>> 2**10 1024 `

Finally, % is for modulus. This gives us the value left after the highest achievable division.

```>>> 13%7
6```

5. Explain identity operators in Python.

The operators ‘is’ and ‘is not’ tell us if two values have the same identity. 1.

```>>> 10 is '10'
False
>>> True is not False
True ```

6. What are numbers?

Python provides us with five kinds of data types:

Numbers – Numbers use to hold numerical values.

```>>> a=7.0
```

7. What are Strings?

A string is a sequence of characters. We declare it using single or double quotes.

`>>> title="Ayushi's Book" `

8. What are Lists?

Lists – A list is an ordered collection of values, and we declare it using square brackets.

`>>> colors=['red','green','blue'] >>> type(colors) `

<class ‘list’>

9. What are Tuples?

Tuples – A tuple, like a list, is an ordered collection of values. The difference. However, is that a tuple is immutable. This means that we cannot change a value in it.

>>> name=(‘Ayushi’,’Sharma’)

>>> name[0]=’Avery’

Traceback (most recent call last):

File “<pyshell#129>”, line 1, in <module>

name[0]=’Avery’

TypeError: ‘tuple’ object does not support item assignment

10. What are Disctionary?

Dictionary – A dictionary is a data structure that holds key-value pairs. We declare it using curly braces.

`>>> squares={1:1,2:4,3:9,4:16,5:25} >>> type(squares) `

<class ‘dict’> 1. >>> type({})

<class ‘dict’> We can also use a dictionary comprehension:

`>>> squares={x:x**2 for x in range(1,6)} >>> squares  {1: 1, 2: 4, 3: 9, 4: 16, 5: 25} `