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How do I delete rows in a data frame?
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The key idea is you form a set of the rows you want to remove, and keep the complement of that set.
In R, the complement of a set is given by the '-' operator.
So, assuming the data.frame is called myData:
myData[-c(2, 4, 6), ] # notice the -
Of course, don't forget to "reassign" ...
HTML / CSS How to add image icon to input type=“button”?
... right align an icon using <input type="button"> , so that the text and the image fit and align nicely?
12 Answers
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Add primary key to existing table
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drop constraint and recreate it
alter table Persion drop CONSTRAINT <constraint_name>
alter table Persion add primary key (persionId,Pname,PMID)
edit:
you can find the constraint name by using the query below:
select OBJECT_NAME(...
Syntax of for-loop in SQL Server
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JOINs (and set operations) should be preferred over looping constructs in SQL.
– Oded
May 20 '11 at 7:58
6
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are there dictionaries in javascript like python?
...x","harry"],
"AK":["liza","alex"],
"TX":["fred", "harry"]
};
And to access the values:
states_dictionary.AK[0] //which is liza
or you can use javascript literal object notation, whereby the keys not require to be in quotes:
states_dictionary={
CT:["alex","harry"],
AK:["...
Reason to Pass a Pointer by Reference in C++?
...hat the user of that class could get a pointer to the internal data buffer and read/write to it, but it cannot – for example – free that buffer using delete or rebind that pointer to some other place in memory? Or did I get it wrong?
– BarbaraKwarc
Aug 4 '1...
logger configuration to log to file and print to stdout
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Just get a handle to the root logger and add the StreamHandler. The StreamHandler writes to stderr. Not sure if you really need stdout over stderr, but this is what I use when I setup the Python logger and I also add the FileHandler as w...
How to generate a simple popup using jQuery
... of div named mail, how can I show a popup window containing a label email and text box?
11 Answers
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How do I get the list of keys in a Dictionary?
I only want the Keys and not the Values of a Dictionary.
9 Answers
9
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When to use AtomicReference in Java?
...e = someFunctionOfOld(cachedValueToUpdate);
boolean success = cache.compareAndSet(cachedValue,cachedValueToUpdate);
Because of the atomic reference semantics, you can do this even if the cache object is shared amongst threads, without using synchronized. In general, you're better off using synchro...