Python-List comprehension

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NCCU, Department of Computer Science
Python Programming for Non-Programmer

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Python-List comprehension

  1. 1. { x|x > 1, x ∈ N } List Comprehension - Quick Generation of ListNCCU, Department of Computer SciencePython Programming for Non-Programmer
  2. 2. List Comprehension Math World: • Components S = {2 · x|x ∈ N, x < 4} • for • if Python World: • else S = [2*x for x in range(1,20) if x<4]NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  3. 3. Case 1 • Q: Generate a list contains square of numbers between 1 and 20. • A: [x**2 for x in range(1,20+1)]NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  4. 4. Case II • Q: Give dictionary D as following: {‘a’:1, ‘b’:2, ‘c’:3, ‘d’:4, ‘e’:5} Please generate the letters who has the value which is greater than or equal 3. • A: for x in D.keys() if D[x]>=3] [x [k for k,v in D.items() if v>=3]NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  5. 5. Practice • Review assignment IV • Warm up for assignment VNCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  6. 6. Practice • Q: It’s about height of people, please design a program to summarize and statistic the data in data file given in TA session. • Data file: pastie.org/1393033 • Architecture file: pastie.org/1393073NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  7. 7. Functions • Load from file • Summary of heights • Lookup a person’s height • Person above a height • Print height report (three in a row)NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  8. 8. Load from file • Load data from a file into a dictionary • Key: name • Value: height • Hint: as what last assignment doesNCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  9. 9. Summary the Height • Print out the following three information: - Highest height - Lowest height - Average height • Hint: try to sort the data by values, and pick up the head and the tail of the sequence.NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  10. 10. Lookup a Height • Ask a name and query the height of it • Hint: as what last assignment doesNCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  11. 11. Person Above Height • Find out who is taller than specific height • Hint: use “List Comprehension”NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  12. 12. Print Report • Enumerate all people and their height each by each • Make output three records in row, like following: a, 152; b,180; c, 190; d, 161; e, 229; f, 191; g, 175; h, 159; • Hint: Embedded a counter to your loopNCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction
  13. 13. That’s all, just do it.NCCU, Department of Computer SciencePython Programming for Non-Programmer {x} List Comprehension Introduction

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