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Pass a data.frame column name to a function
...l_name,col1,col2){
df$col_name <- df$col1 + df$col2
df
}
#Call foo() like this:
foo(dat,z,x,y)
The problem here is that df$col1 doesn't evaluate the expression col1. It simply looks for a column in df literally called col1. This behavior is described in ?Extract under the secti...
Bogus foreign key constraint fail
...each query (bugs.mysql.com/bug.php?id=8280), making it neccessary to write all the drop statements in one query, eg.
SET FOREIGN_KEY_CHECKS=0;
DROP TABLE my_first_table_to_drop;
DROP TABLE my_second_table_to_drop;
SET FOREIGN_KEY_CHECKS=1;
Where the SET FOREIGN_KEY_CHECKS=1 serves as an extr...
How to remove “Server name” items from history of SQL Server Management Studio
When trying to connect to a server in Management Studio (specifically 2008), there is a field where you enter the Server name. That field also has a drop-down list where it shows a history of servers that you have attempted to connect to.
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Use tnsnames.ora in Oracle SQL Developer
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I downloaded and installed the Oracle SQL Developer to connect to an already existing Oracle 11g database. But it seems that I will need to download and install Oracle client software also, which one do I use if I am on Windows 10?
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Run a batch file with Windows task scheduler
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I don't believe you actually need the 'Start in (optional)' value - I am able to run a simple, self-contained .bat file without it. Thank for the clear steps though - very helpful for those looking for a simple walk through!
– ...
Regular Expression For Duplicate Words
...)\s+\b\1\b/
A good selection of test strings can be found here: http://callumacrae.github.com/regex-tuesday/challenge1.html
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#define macro for debug printing in C?
.... } while (0) idiom ensures that the code acts like a statement (function call). The unconditional use of the code ensures that the compiler always checks that your debug code is valid — but the optimizer will remove the code when DEBUG is 0.
If you want to work with #ifdef DEBUG, then change th...
CustomErrors mode=“Off”
...time I upload my webapp to the provider. Because of the customErrors mode, all I see is the default "Runtime error" message, instructing me to turn off customErrors to view more about the error.
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WCF Service , how to increase the timeout?
...re send back and forth "normal" messages, both can be pretty short - especially the receiveTimeout, since receiving a SOAP message, decrypting, checking and deserializing it should take almost no time. The story is different with streaming - in that case, you might need more time on the client to ac...
How to count the number of files in a directory using Python
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For all kind of files, subdirectories included:
import os
list = os.listdir(dir) # dir is your directory path
number_files = len(list)
print number_files
Only files (avoiding subdirectories):
import os
onlyfiles = next(os.w...