Homework 3 - Data extraction, conversion, filter, sort, and build a CSV file output Solution

As discussed in Homework 1 many ETL (extraction, transformation, and load-ing) problems parse data files wherein the data fields is separated by commas. This assignment is a continuation of that process - with an additional two steps. The first step is to convert the input file’s latitude and longitude from sexagesimal (base 60) degrees to decimal degrees. For example, the inputs are in the form: degrees, minutes and seconds, arcseconds and direction. The outputs are in the form: sign, degrees, and decimal fractions to represent the same value.

Therefore this assignment requires the data extraction, degree conversion, data formatting, sorting, and output. The file inputs are defined in the Inputs, as are the outputs.

This assignment has an additional two requirements. The first is to sort the air-ports alphabetically. The second is to sort the airports geographically and plan a route from south to north, all the while flying over land

    • Objectives

The objectives of this assignment are to demonstrate proficiency in file I/O, data struc-tures, data transformation, sorting techniques, and file output using C language re-sources.

1.1    Inputs

There are two basic inputs, the input file name, and the input file data sort order defined below. The input file data is defined below.



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1.1.1    Command Line arguments

The input file name and sort parameters are input from the command line as shown below.

hw3Sort filename.ext sortParameter

In the event that the filename.ext is not available, an appropriate error message shall be displayed. Use the example below for guidance.

hw3Sort ERROR: File “bogusFilename” not found.

It would be appropriate to display the valid sort parameters in the error message. The valid sort parameters are a for alphabetical sort or n for North Bound Exit. The sort parameters can be entered in either upper or lower case.


hw3Sort ERROR: valid sort parameters are a or n.

1.2    Input File fields

The CSV input file contains the following fields. Please note these fields may vary in size, content, and validity of the data. Also note that some of the data formats are a melange of types. Specifically, note that both latitude and longitude contain numbers, punctuation, and text. Likewise, the FAA Site number contains digits, letters, and punctuation. (This assignment will treat all input data as character data. Data conversion for some data is specified in greater detail below.)

1.3    Processing the data structure

The data conversions for this assignment, specified below, require a certain degree of parsing and calculation. Initially reading the input is to your advantage to deal with all data elements as character data. And then process the latitude and longitude, here-inafter referred to as degrees. The degrees are expressed as sexagesimal (base 60) numbers. Therefore it is required to create functions to establish valid latitudes and longitudes.

Please note that there are some airports whose Loc ID begin with numerical digits. There are also quite a few that contain two trailing digits. Typically these are helipads. For the purposes of this assignment those airports can be ignored or discarded from the input. Careful review of these airports will reveal they typically start with the string FL or X and are followed by 2 digits.

Therefore, it is highly recommended to discard any airport that does not contain three or four letters only.






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Table 1: Airports Data Fields

Field Title
Description
Size

FAA Site Number
Contains leading digits fol-
Leading
digits  fol-

lowed by a decimal point
lowed by a decimal

and short text
point and zero to two


digits and a letter
Loc ID
The airport’s short name, i.e.
4 characters

MCO for Orlando


Airport Name
The airport’s full name, i.e.
~30 characters

Orlando International


Associated City
The nearest city
~25 characters
State
State
2 characters
Region
FAA Region
3 characters
ADO
Airline Dispatch Office
3 characters
Use
Public or Private
2 characters
Latitude
DD-MM-SS.MASDirection
Degrees,
minutes,


seconds,
milliarc-


seconds followed by


either N or S.
Longitude
DD-MM-SS.MASDirection
Degrees,
minutes,


seconds,
milliarc-


seconds followed by


either E or W.
Airport Ownership
Public or Private
2 characters
Part 139
FAA Regulation
No data

NPIAS Service Level
National  Plan  Integrated
~10 characters

Airport Systems Descriptor


NPIAS Hub Type
Intentionally left blank
n/a

Airport Control Tower
Y/N
one character
Fuel
Fuel types available
up to 6 characters
Other Services
Collections of tag indicating
12 characters

INSTRuction, etc.


Based Aircraft Total
Number of aircraft (may be
Integer number

blank)


Total Operations
Takeoffs/Landings/etc (may
Integer number

be blank)









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1.3.1    Latitude/Longitude Input

The latitude and longitude are both degrees, expressed as shown in the tables below.


Table 2: Degrees

Placeholder
Name
Value
Decimal
DD
Degrees
180
0-180
MM
Minutes
0-59

value




60

SS.MAS
Seconds.MilliArcSeconds
0-59.0-9999

value




602

D
Direction
N,S,E,W
See Table 3




Table 3: Direction

Unit
Name
Decimal Sign
Latitude
N
+

S
-



Longitude
E
+

W
-





The conversion of the DDD-MM-SS.MASD string is shown in Table 2. The for-mula to convert a sexagesimal degree measurement to a digital degree measurement is shown below.

degreesdecimal =    DDD + MM=60 + SS:MAS=602

Note that the    is derived from the information in Table 3 above.

1.4    Functions

1.4.1    float sexag2decimal(char *degreeString);

Description: Convert the sexagesimal input string of chars to a decimal degree based on the formula in Tables 2 and 3.

Special Cases: If a NULL pointer is passed to this function, simply return 0.0. Sim-ilarly, if the DD-MM-SS.MASD fields have invalid or out-of-range data, return 0.0.

Caveat: Even though the valid range of Degrees is from 0 to 180, the data files for the Continental US and Florida are from 0 to 99. Make sure that the conversion can handle all valid cases correctly.



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Hint: Take care to make sure the values for each numeric component are within their valid ranges. Refer to Table 2 for the ranges.

Returns: A floating point representation of the calculated decimal degrees or 0.0 in the special cases mentioned above.

1.4.2    void sortByLocID(lListAirPdata *airports);

Description: Sorts the airports alphabetically by the string named Loc ID. Remember that the Loc ID has been filtered to three or four letters.

Special Cases: Remember the helipads! In other words, it is recommended to skip airports whose Loc ID begin with a number, or start with either FL or X followed by two digits. Therefore, it is recommended to discard any airport whose LocID is not three or four letters.

Caveat: Since the sorting options are mutually exclusive, this function can destruc-tively manipulate the input list to produce the desired results.

Returns: Nothing. However the input data should be seriously modified by this pro-cess.

1.4.3    void sortByLatitude(lListAirPdata *airports);

Description: Sorts the airports by latitude from South to North. Think of this as an Escape from Key West to Georgia.

Special Cases: Remember the helipads! In other words, it is acceptable to skip air-ports whose Loc ID begin with a number, or start with either FL or X followed by two digits. Remember, it is recommended to discard any Loc ID that does not contain three or four letters only.

Output: Output the airports’ data per the output file specification derived from walk-ing thru the AVL tree until reaching the maximum latitude for the Florida border. For the purposed of this exercise, assume 31 degrees North.

Caveat: Since the sorting options are mutually exclusive, this function can destruc-tively manipulate the input list to produce the desired results.

Hint: Remember to use the the converted Latitude as a measurement criteria for build-ing an AVL tree.

Returns: Nothing. However the input data could be seriously modified by this pro-cess.





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    • Outputs

The outputs of the program will be populated Struct airPdata data. This data will be formatted so as to provide output as defined in the following sections.

2.1    Data Structure

The structure struct airPdata is described below. Please note the correlation with the data file’s Field Names refer to Table 1 on page 3 for more information. NB The Javascript APIs and many other APIs for plotting geographic data REQUIRES that longitude is before latitude.


typedef struct airPdata{
char *LocID;    //Airport’s ‘‘Short Name’’, ie MCO
char *fieldName; //Airport Name
char *city;    //Associated City
float longitude; //Longitude

float latitude; //Latitude

} airPdata;



2.2    File output

The file output for this assignment is stdout, aka the console. Make sure there is a headline that names each column. For example:

code,name,city,lat,lon

DAB,DAYTONA BEACH INTL,DAYTONA BEACH,29.1797,-81.0581

FLL,FORT LAUDERDALE/HOLLYWOOD INTL,FORT LAUDERDALE,26.0717,-80.1494

GNV,GAINESVILLE RGNL,GAINESVILLE,29.6900,-82.2717

JAX,JACKSONVILLE INTL,JACKSONVILLE,30.4939,-81.6878

EYW,KEY WEST INTL,KEY WEST,24.5561,-81.7594

LAL,LAKELAND LINDER RGNL,LAKELAND,27.9889,-82.0183

MLB,MELBOURNE INTL,MELBOURNE,28.1025,-80.6450

MIA,MIAMI INTL,MIAMI,25.7953,-80.2900

APF,NAPLES MUNI,NAPLES,26.1522,-81.7756

SGJ,NORTHEAST FLORIDA RGNL,ST AUGUSTINE,29.9592,-81.3397

ECP,NORTHWEST FLORIDA BEACHES INTL,PANAMA CITY,30.3581,-85.7956

OCF,OCALA INTL-JIM TAYLOR FIELD,OCALA,29.1717,-82.2239

MCO,ORLANDO INTL,ORLANDO,28.4292,-81.3089

Things to note:

Digital degrees are expressed as floating point numbers of varying digits of pre-cision. This is an artifact of Javascript usage by many APIs. In this exercise 4 digits to the right of the decimal point is sufficient.

The first line of the file identifies the field names. This is a material fact and will adversely impact the output of the data in the webpage. Capitalization and spelling matter - and must match the first line above.

The text shown above has been converted to uppercase as a piece of information to help debugging. String case conversion is not required for this exercise.


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    • Processing

The primary goal is to provide programmatic access to the data from the input CSV file. This must be accomplished using standard C file IO techniques. Also note that it is vital to utilize the stuct airPdata for all data retrieval/extraction and conversion. Likewise, use of the stuct airPdata is required for the file output.

3.1    Reading the input

There are several approaches to read the input. Perhaps the most important considera-tion is reading the line in for each airport. Please note that there is one line per airport. Also note, that once the line is read into the input buffer it might be advantageous to parse the input buffer based on the comma delimiter.

There are several approaches possible. Make sure to test on Eustis as line termina-tion characters/behaviors vary amongst operating systems.

Make sure that the output is formatted with decimal degrees.

3.2    Testing

The input files used in Homework 1 will be used as an additional testing file. Errors may be induced for the degrees.

There will be two files provided for program testing. They are described below.


Table 4: Test Files



Filename

Description
FL-airports-PLOT.csv

All 25 airports’ data formatted as defined


in the Output Specification.
FL-ALL.csv

All 874 airports, including helipads, in


Florida.
FL-RAW-airports.csv

A list of the 25 public Florida airports,


wherein all the data is formatted as defined


in the Input Specfication.
orlando.csv

25 airports, including helipads, near Or-


lando.
orlando3BadDegrees.csv

25 airports, including helipads, near Or-


lando.  3 of the airports have bogus data


in a degree field.







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    • Grading

Scoring will be based on the following rubric:


Table 5: Grading Rubric


Percentage
Description
-100
Cannot compile on Eustis
- 50
Cannot accept input filename as command line argu-

ment
- 30
Cannot read input file

Cannot output valid csv formatted data

    • 15 Severe deviations from csv format (eg. printing wrong fields, or excessive junk lines, or nothing)

    • 10 Moderate deviations from csv format (eg. has format-ted columns)

        ◦ 5 Only minor deviations from csv format (eg. an extra space or comma here or there)

    • 15   Printed nothing

    • 10   Printed only a few airports

        ◦ 5   Only missing one or two airports


Does not correctly convert latitude or longitude to decimal degrees


    • 30   Does not convert at all

    • 20   Converts, but has many computational errors

    • 10   Converts, with 10 or fewer errors

Note: While perfect accuracy is an achievable stan-

dard for this conversion, your numbers are consid-

ered correct if they are within +/- 0.0002 of the actual

value.


Does not catch errors in degrees fields

    • 10   Does not catch errors in degrees fields.

        ◦ 5   Catches some but not all errors




    • Submission Instructions

The assignment shall be submitted via WebCourses. There should be one file in the submission.

The main source file named hw3Sort.c

A comment in the source file containing the following statement -“Your state-ment that the program is entirely your own work and that you have neither de-veloped your code together with any another person, nor copied program code

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from any other person, nor permitted your code to be copied or otherwise used by any other person, nor have you copied, modified, or otherwise used program code that you have found in any external source, including but not limited to, online sources”



















































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