如何将以下Scala代码转换为python

Question

Here is a Pattern matching switch case in Scala, which basically matches different data types of the selector variable to the corresponding case variable and does some manipulation on it

def valueToString(x: Any): String = x match {

        case d: BigDecimal =>
          /* do something here */

        case a: Array[Byte] =>
          new String(a, "UTF-8")

        case s: Seq[_] =>
          /*do something here */

        case m: Map[_,_] =>
         /*do something here */

        case d: Date =>
          /*do something here */

        case t: Timestamp =>
          /*do something here */

        case r: Row =>
        /*do something here */
       }

Python does not have exactly support this kind of pattern matching. I know about switcher in Python, but it expects either regex or actual matching of the variable. How do i achieve the above functionality in Python

Answer 1

Type checking

Use isinstance method to check the type of your generic input

import datetime

def value_to_string(input):

    # String
    if isinstance(input, basestring):
        return 'string'

    # BigDecimal
    if isinstance(input, int):
        return 'int'

    # Array
    if isinstance(input, list):
        return 'list'

    # Map
    if isinstance(input, dict):
        return 'dictionary'

    # Date
    if isinstance(input, datetime.date):
        return 'date'

    # ...

usage

print value_to_string('')
print value_to_string(1234)
print value_to_string([1,2,3])
print value_to_string({"id": 1})
print value_to_string(datetime.datetime.now())

output

string
int
list
dictionary
date