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Warning message: In `…` : invalid factor level, NA generated
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If you are reading directly from CSV file then do like this.
myDataFrame <- read.csv("path/to/file.csv", header = TRUE, stringsAsFactors = FALSE)
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improv...
Android Studio Stuck at Gradle Download on create new project
...tely, I'd recommend shutting down Android Studio (may have to force kill), then going to your ~/.gradle directory on the console. You'll see a wrapper/dists directory there and whatever version of gradle AS is trying to download. Check the timestamp of the download underneath the randomly named subd...
Convert from enum ordinal to enum type
...e ReportTypeEnum that get passed between methods in all my classes but I then need to pass this on the URL so I use the ordinal method to get the int value. After I get it in my other JSP page, I need to convert it to back to an ReportTypeEnum so that I can continue passing it.
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Make a negative number positive
...e are so many equally good answers, that I might as well delete mine. But then I'd lose 40 points, and I'll never catch Jon Skeet if I do that.
– Paul Tomblin
Jan 29 '09 at 21:53
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how to check the jdk version used to compile a .class file [duplicate]
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addendum: You can put -cp <jar> then the class so you can get it from and existing jar
– Christian Bongiorno
Dec 4 '14 at 17:32
2
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Java: Detect duplicates in ArrayList?
...llection into a Set (using the Set(Collection) constructor or Set.addAll), then see if the Set has the same size as the ArrayList.
List<Integer> list = ...;
Set<Integer> set = new HashSet<Integer>(list);
if(set.size() < list.size()){
/* There are duplicates */
}
Update: ...
Unix tail equivalent command in Windows Powershell
...before Get-Content will work. If the writing process never closes the file then it won't work which is not the case with tail -f.
– David Newcomb
Mar 31 '12 at 20:01
15
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What's “P=NP?”, and why is it such a famous question? [closed]
...P means that if a problem takes polynomial time on a non-deterministic TM, then one can build a deterministic TM which would solve the same problem also in polynomial time. So far nobody has been able to show that it can be done, but nobody has been able to prove that it cannot be done, either.
NP...
Java 8: Lambda-Streams, Filter by Method with Exception
...g a method which literally can never throw the exception that it declares, then you should not include the throws clause.
For example: new String(byteArr, "UTF-8") throws UnsupportedEncodingException, but UTF-8 is guaranteed by the Java spec to always be present.
Here, the throws declaration is a ...
Force drop mysql bypassing foreign key constraint
... = 1;
SET foreign_key_checks = 0 is to set foreign key checks to off and then SET foreign_key_checks = 1 is to set foreign key checks back on. While the checks are off the tables can be dropped, the checks are then turned back on to keep the integrity of the table structure.
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