Created
March 8, 2016 20:31
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Ruby method to convert zero-based indices into excel column names (like, "AAB").
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| require 'minitest/autorun' | |
| # Turns an zero-based index into an excel column name | |
| def excel_column_name(i) | |
| digits = ("A".."Z").to_a | |
| return digits[i] if i < 26 | |
| "#{excel_column_name(i/26 - 1)}#{excel_column_name(i % 26)}" | |
| end | |
| class ExcelColumnNameTest < Minitest::Test | |
| def test_n_less_than_26 | |
| assert_equal("G", excel_column_name(7 - 1)) | |
| end | |
| def test_n_greater_than_26 | |
| assert_equal("AA", excel_column_name(27 - 1)) | |
| assert_equal("AZ", excel_column_name(52 - 1)) | |
| end | |
| def test_two_excel_digits | |
| assert_equal("BA", excel_column_name(52)) | |
| assert_equal("BZ", excel_column_name(77)) | |
| end | |
| def test_three_excel_digits | |
| assert_equal("ZA", excel_column_name(26 * 26)) | |
| assert_equal("ZZ", excel_column_name(26 * 26 + 26 - 1)) | |
| assert_equal("AAA", excel_column_name(26 * 26 + 26)) | |
| end | |
| end |
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