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← Reading Excel Files - Data Wranging with MongoDB

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Showing Revision 2 created 05/24/2016 by Udacity Robot.

  1. Great job making it this far into the course.
  2. Let's take a look at the solution to this XORD
  3. exercise. So here's our parse file function, and you
  4. can see that what we've done here, is use this
  5. column slicing trick. We've used the call values method
  6. on sheet to pull out all of the values in
  7. column one. Column one being the coast column within
  8. that data set. Then, we're simply using max and min
  9. here on this list that we've pulled out, in order to get the max val and min
  10. val in that entire column. We're using the index
  11. method on lists, to figure out where that max
  12. val is in the CV list. Now, because the
  13. data that we have actually begins on row one
  14. of the spreadsheet rather than row zero, we've got
  15. to add a one here. So that within our
  16. spreadsheet, we end up with the right position for
  17. that value, that is to say, the right row
  18. number. Okay, then what we're going to do here is
  19. for the position or the row on which the
  20. max value appears, we're going to take the value
  21. in column zero. That will give us the max
  22. time. Okay? And then what we're going to do,
  23. is turn that time, which we'll get as a floating
  24. point number, into an actual time tuple. We'll
  25. do that same process with the min value.
  26. In generating our data dictionary that we'll end
  27. up returning from this function, we can simply
  28. plug in the realtime, maxval, realmintime, and minval,
  29. and then to get the average, we're simply
  30. going to calculate it right here, and make
  31. it the value of this key, avgcoast. Okay,
  32. let's run this. I just want to point out that I'm using the p print
  33. module here, so that we get our data printed out in a nicely structured way.
  34. And we can see that we get good values here.
  35. And if you take a look in the spreadsheet itself
  36. and do something like sort the spreadsheet, you'll see that
  37. the maximum times and the maximum values are calculated correctly. One
  38. thing I want to note is that, in our assertion here,
  39. we're doing a rounding so that we don't have any
  40. issues with floating point values being slightly off as we
  41. get further and further to the right of the decimal point.