# How to round a number in python ?

Examples of how to round a number in python:

### Round a float number

To round a number in python, a solution is to use the function round :

````>>> round(3.1415)`
`3`
```

### Round a float number (keep 1 digit after the decimal point)

````>>> x = 1.4567`
`>>> round(x,1)`
`1.5`
```

### Round a float number (keep 2 digits after the decimal point)

````>>> x = 1.4567`
`>>> round(x,2)`
`1.46`
```

### Change a float to int

````>>> x = 3.1415`
`>>> x = int(x)`
`>>> x`
`3`
`>>> type(x)`
`<class 'int'>`
```

same as

````>>> x = round(3.1415)`
`>>> type(x)`
`<class 'int'>`
`>>> x`
`3`
```

### Round the elements of an array

To round the element of an array a solution is to use the numpy function around, example:

````>>> import numpy as np`
`>>> a = np.array(([1.24,3.46,5.34]))`
`>>> a`
`array([1.24, 3.46, 5.34])`
`>>> np.around(a, decimals=1)`
`array([1.2, 3.5, 5.3])`
```

To convert a float array to a integer array, a solution is to use astype:

````>>> import numpy as np`
`>>> a = np.array(([1,24,3.46,5.34]))`
`>>> a`
`array([ 1.  , 24.  ,  3.46,  5.34])`
`>>> a.astype(int)`
`array([ 1, 24,  3,  5])`
```

### Round a complex number

````>>> z = 2.14 + 3.47j`
`>>> round(z.real, 1) + round(z.imag, 1) * 1j`
`(2.1+3.5j)`
```

### Use format

if the goal of rounding a number is to add it to a string, a solution is to use format()

````>>> s = 'Pi value is {:06.2f}'.format(3.141592653589793)`
`>>> s`
`'Pi value is 003.14'`
`>>> s = 'Pi value is {:01.2f}'.format(3.141592653589793)`
`>>> s`
`'Pi value is 3.14'`
```