How do I know what type my variable is?

You can use the builtin type function to check the type of a variable.

import numpy as np np.random.seed(0) n = 10000 x = np.random.standard_normal(n) print(type(x)) # numpy.ndarray 

If, in the specific case of numpy, you want to check the type of your elements, then you can do

print(x.dtype) # dtype('float64') 

Python is a dynamically typed language. Technically, when reading code, you won't be able to know the type of a variable without following the code, or if the code is excessively simple.

A few quotes for you:

Python is strongly typed as the interpreter keeps track of all variables types. It's also very dynamic as it rarely uses what it knows to limit variable usage.

In Python, it's the program's responsibility to use built-in functions like isinstance() and issubclass() to test variable types and correct usage.

You can use isinstance(x, type) or type(x) to learn about the variables type information at runtime.

Use dtype:

n = 10000 x = np.random.standard_normal(n) x.dtype 

gives:

dtype('float64') 

If you want more detailed information on the array attributes, you could use info:

np.info(x) 

gives:

class: ndarray shape: (10000,) strides: (8,) itemsize: 8 aligned: True contiguous: True fortran: True data pointer: 0xba10c48 byteorder: little byteswap: False type: float64 

type(x) is straitforward answer. Normally you don't test type it through type but use isinstance(x, type) to test it.

in the REPL (interactive console), you can also do

>>> help(x) 

and it will display information about x's class, including it's methods.