Type casting with astype() in NumPy - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the astype() method do in NumPy?

The astype() method converts the data type of a NumPy array to another specified type, creating a new array with the new type.

beginner

How do you convert a NumPy array of floats to integers using astype()?

Use array.astype(int) to convert all elements from float to integer type.

beginner

Does astype() modify the original array or create a new one?

astype() creates a new array with the new type and does not change the original array.

intermediate

What happens if you convert a float array with decimal values to integers using astype()?

The decimal part is truncated (cut off), so values are converted to their integer part only.

intermediate

Can you use astype() to convert a NumPy array to a string type?

Yes, you can convert a NumPy array to string type by using astype(str).

What does array.astype(float) do?

A Changes the original array in place

B Converts array elements to float type

C Deletes the array

D Converts array elements to string type

astype(float) creates a new array with elements converted to float type without changing the original array.

If you convert np.array([1.9, 2.5, 3.7]) to int using astype(int), what is the result?

A [1, 2, 3]

B [1.9, 2.5, 3.7]

C [1, 2, 3] but as floats

D [2, 3, 4]

Converting floats to int truncates decimals, so values become [1, 2, 3].

Does astype() modify the original NumPy array?

A Yes, it changes the original array

B It deletes the original array

C No, it returns a new array with the new type

D It only works on lists

astype() returns a new array and leaves the original unchanged.

Which of these is a valid way to convert a NumPy array to string type?

A array.convert(str)

B array.astype(int)

C array.to_string()

D array.astype(str)

astype(str) converts array elements to string type.

What happens if you try to convert a string array with non-numeric text to int using astype(int)?

A It raises a ValueError

B Conversion succeeds with no errors

C It converts all to zero

D It converts to float instead

Trying to convert non-numeric strings to int raises a ValueError because conversion is not possible.

Explain how to use astype() to change the data type of a NumPy array and what happens to the original array.

Think about whether the original data changes or not.

Describe what happens when converting a float array with decimal values to integers using astype().

Consider how decimals are handled when changing to int.