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HHMathewChan
HHMathewChan

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Python syntax learning 1: Convert float to int

Inspired from yesterday exercise , I search for is there any other way to convert a object from float to integer?
The following is my findings:
and small conclusion at the end

There are four syntax available:

  1. int()
  2. math.trunc()
  3. math.floor()
  4. math.celi()

Method 1. int()

Syntax:

int(x)
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Parameter:

x can be a string or number
but only one.
example 1
The string can only be an integer number

str1 = "5" 
int(str1)
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example 2
If the parameter is not a string, it can have decimal point

str2 = 5.12  
int(str2)
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The following code will cause error:

str1 = "5,6" # more than one number in a string
str2 = "4.8" # the number in string must in integer
int(str1)
int(str2)
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What object will int()be return?

an int object will be returned
which cut off all the number after decimal place
example 1.

str1 = "5"
int(str1)
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will have an output
5
example 2

str2 = 5.12
int(str2)
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will have an output
5


Method 2. math.trunc()

  • need to import math module before use ### Syntax
import math

math.trunc(x)
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Parameter

  • math.trunc()only takes number as parameter e.g.
math.trunc(5.123)
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What object will math.trunc() return?

  • an integer will returned
  • which will cut off all the fractional part after decimal place
  • same as int()

example

import math

num2 = 5
int2 = math.trunc(num2)
print(int2)
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will have an output
5


Method 3. math.floor()

  • need to import math module before use ### Syntax
import math

math.floor(x)
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Parameter

math.floor() can only take number as parameter

What object will math.floor() return?

an integer will returned.
The number will be round down

  • that is the largest integer less than or equal to x

example

import math

num2 = 5.9
int2 = math.floor(num2)
print(int2)

num3 = 5.1
int3 = math.floor(num3)
print(int3)
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both num2 and num3 will have an output

5

Method 4. math.ceil()

  • need to import math before use
import math

math.celi(x)
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Parameter

math.celi() can only take number as parameter

What object will math.floor() return?

an integer will returned.
The number will be round up.

  • that is the smallest integer greater than or equal to x

example

import math

num2 = 5.9
int2 = math.floor(num2)
print(int2)

num3 = 5.1
int3 = math.floor(num3)
print(int3)
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both num2 and num3 will have an output
6

Conclusion

  • int() is the most flexible way to convert float object to integer, but will suffer from data lose, same as meth.trunc().
  • math.floor() and math.celi() can minimize data lose in the conversion if use properly.

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