ML_for_Hackers
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johnmyleswhite
filter out malformed date data of ufo
It's about the first chapter that you use string length of 8 to deal with malformed date data. After using string length to filter out malformed data, I found "19940000" in DateOccurred and it will be transformed to "NA" by using "ufo$DateOccurred<-as.Date(ufo$DateOccurred, format="%Y%m%d")" after converting date strings. Isn't it also malformed data? And I also found that the way R read the input has an error: like the line 756:
19950704 19950706 Orlando, FL 4-5 min I would like toreport three yellow oval lights which passed over Orlando,Florida on July 4, 1995 at aproximately 21:30 (9:30 pm). These were the sizeof Venus (which they passed close by). Two of them traveled one after the otherat exactly the same speed and path heading south-southeast. The third oneappeared about a minute later following the same path as the other two. Thewhole sighting lasted about 4-5 minute. There were 4 other witnesses oldenough to report the sighting. My 4 year old and 5 year old children were theones who called my attention to the "moving stars". These objects moved fasterthan an airplane and did not resemble anaircraft, and were moving much slowerthan a shooting star. As for them being fireworks, their path was too regularand coordinated. If anybody else saw this phenomenon, please contact me at: [email protected]
After reading in by the function in the book:
> ufo <- read.delim(file.path("data", "ufo", "ufo_awesome.tsv"),
+ sep = "\t",
+ stringsAsFactors = FALSE,
+ header = FALSE,
+ na.strings = "")
it's separated into two lines:
> ufo[756,]
V1 V2 V3 V4 V5 V6
756 [email protected] <NA> <NA> <NA> <NA> <NA>
> ufo[755,]
V1 V2 V3 V4 V5
755 19950704 19950706 Orlando, FL <NA> 4-5 min
V6
755 I would like to report three yellow oval lights which passed over Orlando,Florida on July 4, 1995 at aproximately 21:30 (9:30 pm). These were the sizeof Venus (which they passed close by). Two of them traveled one after the otherat exactly the same speed and path heading south- southeast. The third oneappeared about a minute later following the same path as the other two. Thewhole sighting lasted about 4-5 minutes. There were 4 other witnesses oldenough to report the sighting. My 4 year old and 5 year old children were theones who called my attention to the "moving stars". These objects moved fasterthan an airplane and did not resemble an aircraft, and were moving much slowerthan a shooting star. As for them being fireworks, their path was too regularand coordinated. If anybody else saw this phenomenon, please contact me at:
