lab07 practice problems#38
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ykharitonova
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Nov 20, 2019
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| # Extra practice | ||
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| 1. Write a function `set_intersection(A, B)` that takes two lists of numbers A and B as inputs, and returns a list containing all numbers common to both input lists. If a number occurs n times in both lists, it should occur n times in the result. The order of the result should be the order of occurrence in the first input list. Examples: `set_intersection([1, 8, 2, 1], [4, 1, 8])` should return `[1, 8]`; `set_intersection([8, 1, 2, 1], [4, 1, 8, 1])` should return `[8, 1, 1]`. |
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The first and second problems are good practice exercises. I would call it get_intersection
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| 2. Write a function that concatenates two input files (reads them and combines them into one by putting one after the other) and writes the result to an output file: `concatenate(infile1, infile2, outfile)`. | ||
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| 3. Write a function that takes a dict of filename-word pairs as input, splits each file at each occurrence of its associated word, and writes an output file for each split. `split_files({"animals.txt": "giraffe", "dinosaur.txt": "velociraptor"})` should read "animals.txt", split it up into n+1 chunks where the chunks are bounded by n occurrences of the word "giraffe" (no final chunk should contain the word "giraffe"), and write the chunks to output files "giraffe1.txt", ..., "giraffe\<n\>".txt. Then it should do the same for the dinosaur file. Note: you may want to start by writing a helper function. |
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This is confusing, esp. since it might not be clear to them what the helper function is supposed to do.
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| 3. Write a function that takes a dict of filename-word pairs as input, splits each file at each occurrence of its associated word, and writes an output file for each split. `split_files({"animals.txt": "giraffe", "dinosaur.txt": "velociraptor"})` should read "animals.txt", split it up into n+1 chunks where the chunks are bounded by n occurrences of the word "giraffe" (no final chunk should contain the word "giraffe"), and write the chunks to output files "giraffe1.txt", ..., "giraffe\<n\>".txt. Then it should do the same for the dinosaur file. Note: you may want to start by writing a helper function. | ||
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| 4. Write functions implementing the string methods `split`, `isnumeric`, `replace`, and `join`. For example, `replace("hello world", "l", "_")` should return "he__o world". In a Python interpreter, run `dir("")` to get a list of other string methods that might be good practice candidates. |
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Are they supposed to re-implement the available functions?
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| 4. Write functions implementing the string methods `split`, `isnumeric`, `replace`, and `join`. For example, `replace("hello world", "l", "_")` should return "he__o world". In a Python interpreter, run `dir("")` to get a list of other string methods that might be good practice candidates. | ||
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| 5. Write a function that "rotates" a dictionary of string-int pairs by a given shift value: return a dictionary where each value is assigned to the key that is `shift` keys away from its original key, where the ordering of keys is defined by alphabetical sorting. For example: `rotate_dict({"guitar": 4, "violin": 9, "banjo": -3, "cello": 0}, 2)` should return `{"guitar": -3, "violin": 0, "banjo": 9, "cello": 4}`. |
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What's the real-world example for when to use this function?
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Sections for lab07 have already started but we could add these anyway and make an announcement about it