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Variables and References in Python

Variables and References in Python. "TAGAGAATTCTA”. s. Names. Objects. References. >>> s = “TAGAGAATTCTA” >>>. "TAGAGAATTCTA". s. "GAAT". t. Names. Objects. References. >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>>. "TAGAGAATTCTA". s. "GAAT". t. 4. i. Names. Objects.

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Variables and References in Python

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  1. Variables and References in Python

  2. "TAGAGAATTCTA” s Names Objects References >>> s = “TAGAGAATTCTA” >>>

  3. "TAGAGAATTCTA" s "GAAT" t Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>>

  4. "TAGAGAATTCTA" s "GAAT" t 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> Strings have a “find” method

  5. "TAGAGAATTCTA" s "GAAT" t 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> t = s >>>

  6. "TAGAGAATTCTA" s t 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> t = s >>>

  7. "TAGAGAATTCTA" s t 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> t = s >>> a Traceback (most recent call last): File "<stdin>", line 1, in ? NameError: name 'a' is not defined >>>

  8. "TAGAGAATTCTA" s "GA" t 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> t = s >>> a Traceback (most recent call last): File "<stdin>", line 1, in ? NameError: name 'a' is not defined >>> s = “GA” >>> print t TAGAGAATTCTA >>>

  9. s "GA" 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> t = s >>> a Traceback (most recent call last): File "<stdin>", line 1, in ? NameError: name 'a' is not defined >>> s = “GA” >>> print t TAGAGAATTCTA >>> del t >>>

  10. s "GA" 4 i Names Objects References >>> s = “TAGAGAATTCTA” >>> t = “GAAT” >>> i = s.find(t) >>> print i 4 >>> t = s >>> print a Traceback (most recent call last): File "<stdin>", line 1, in ? NameError: name 'a' is not defined >>> s = “GA” >>> print t TAGAGAATTCTA >>> del t >>> print t Traceback (most recent call last): File "<stdin>", line 1, in ? NameError: name 't' is not defined >>>

  11. [2, 4] L1 Names Objects References >>> L1 = [2, 4] >>>

  12. [2, 4, 5] L1 Names Objects References >>> L1 = [2, 4] >>> L1.append(5) >>>

  13. [2, 4, 5] L1 L2 Names Objects References >>> L1 = [2, 4] >>> L1.append(5) >>> L2 = L1 >>>

  14. [2, 4, 5, 7] L1 L2 Names Objects References >>> L1 = [2, 4] >>> L1.append(5) >>> L2 = L1 >>> L2.append(7) >>> print L1 [2, 4, 5, 7] >>> print L2 [2, 4, 5, 7] >>>

  15. [2, 5, 7] L1 L2 Names Objects References >>> L1 = [2, 4] >>> L1.append(5) >>> L2 = L1 >>> L2.append(7) >>> print L1 [2, 4, 5, 7] >>> print L2 [2, 4, 5, 7] >>> del L2[1] >>>

  16. [2, 5, 7] L1 [2, 5, 7] L2 Names Objects References >>> L1 = [2, 4] >>> L1.append(5) >>> L2 = L1 >>> L2.append(7) >>> print L1 [2, 4, 5, 7] >>> print L2 [2, 4, 5, 7] >>> del L2[1] >>> L2 = L1[:] >>> L1 == L2 True >>>

  17. [7, 5, 2] L1 [2, 5, 7] L2 Names Objects References >>> L1 = [2, 4] >>> L1.append(5) >>> L2 = L1 >>> L2.append(7) >>> print L1 [2, 4, 5, 7] >>> print L2 [2, 4, 5, 7] >>> del L2[1] >>> L2 = L1[:] >>> L1 == L2 True >>> L1.reverse() >>> L1 == L2 False >>>

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