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Answer: NumPy supports a much greater variety of numerical types than Python does. NumPy numerical types are instances of numpy.dtype (data-type) objects, each having unique characteristics. (S1)

Basics

• There are 5 basic numerical types representing booleans (bool), integers (int), unsigned integers (uint) floating point (float) and complex. (S1)
• You can create arrays with a specified dtype using the scalar types in the numpy top-level API, e.g. numpy.bool, numpy.float32. (S1)
• dtype objects also contain information about the type, such as its bit-width and its byte-order. (S1)
• To convert the type of an array, use the .astype() method. (S1)

In practice

• All elements of the array must be of the same type of data. (S2)
• The data type is recorded in the dtype attribute. (S2)
• While the default data type is floating point (np.float64), you can explicitly specify which data type you want using the dtype keyword. (S2)

Claims

• id: C1 claim: NumPy has more numerical types than Python. source: S1 evidence: "NumPy supports a much greater variety of numerical types than Python does."
• id: C2 claim: Use .astype() to convert an array's type. source: S1 evidence: "To convert the type of an array, use the .astype() method."
• id: C3 claim: All array elements share one data type. source: S2 evidence: "All elements of the array must be of the same type of data."
• id: C4 claim: The default data type is np.float64. source: S2 evidence: "While the default data type is floating point (np.float64)"

Sources

• [S1] Data types — NumPy v2.5 Manual. NumPy docs. https://numpy.org/doc/stable/user/basics.types.html . License: BSD-3-Clause (numpy/numpy LICENSE.txt; Copyright (c) 2005-2026, NumPy Developers; https://github.com/numpy/numpy/blob/main/LICENSE.txt). Accessed 2026-11-04.
• [S2] NumPy: the absolute basics for beginners — NumPy v2.5 Manual. NumPy docs. https://numpy.org/doc/stable/user/absolute_beginners.html . License: BSD-3-Clause (numpy/numpy LICENSE.txt; Copyright (c) 2005-2026, NumPy Developers; https://github.com/numpy/numpy/blob/main/LICENSE.txt). Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).

@misc{iil_note_sm4rbc8j,
  author = {{iinventedlight}},
  title = {{NumPy data types (dtype)}},
  howpublished = {iinventedlight Library},
  year = {2026},
  date = {2026-11-04},
  url = {https://iinventedlight.com/library/notes/numpy-dtypes/},
  note = {Permanent ID iil:note:sm4rbc8j. License: CC-BY-4.0.},
}

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