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Convert column classes in data.table
...
105
For a single column:
dtnew <- dt[, Quarter:=as.character(Quarter)]
str(dtnew)
Classes ‘d...
How to run crontab job every week on Sunday
...
10 Answers
10
Active
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Modifying a subset of rows in a pandas dataframe
...fy this DataFrame (or create a copy) so that B is always NaN whenever A is 0. How would I achieve that?
5 Answers
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How to write the Fibonacci Sequence?
...rning the Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 should = only those numbers between 1 & 20), I have written for the program to display all Fibonacci numbers between a range (ie. startNumber 1, endNumber 20 displays = First 20 Fibonacci numbers). I thought I had a sure-fi...
How to remove convexity defects in a Sudoku square?
...Y = ImageMultiply[MorphologicalBinarize[GaussianFilter[srcAdjusted, 3, {2, 0}], {0.02, 0.05}], mask];
lX = ImageMultiply[MorphologicalBinarize[GaussianFilter[srcAdjusted, 3, {0, 2}], {0.02, 0.05}], mask];
I use connected component analysis again to extract the grid lines from these images. The g...
How to check whether a pandas DataFrame is empty?
...
505
You can use the attribute df.empty to check whether it's empty or not:
if df.empty:
print(...
“CASE” statement within “WHERE” clause in SQL Server 2008
...ery which contains "CASE" statement within "WHERE" clause. But SQL Server 2008 is giving some errors while executing it. Can anyone please help me with the correct query? Here is the query:
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C++/COM VARIANT实现二维数组 - C/C++ - 清泛网 - 专注C/C++及内核技术
...ND sab[2]; /*用于定义数组的维数和下标的起始值*/
sab[0].cElements = 2;
sab[0].lLbound = 0;
sab[1].cElements = 2;
sab[1].lLbound = 0;
/*创建一个2*2的类型为long的二维数组*/
SAFEARRAY* psa = SafeArrayCreate(vt, sizeof(sab)/sizeof(SAF...
Shell equality operators (=, ==, -eq)
... guaranteed to work.
$ a=foo
$ [ "$a" = foo ]; echo "$?" # POSIX sh
0
$ [ "$a" == foo ]; echo "$?" # bash specific
0
$ [ "$a" -eq foo ]; echo "$?" # wrong
-bash: [: foo: integer expression expected
2
(Side note: Quote those variable expansions! Do not leave out the double quotes ab...
How to use if - else structure in a batch file?
... to d
copy "%sourceFile%" "%destinationFile%"
)
IF %F%==1 IF %C%==0 (
::moving the file c to d
move "%sourceFile%" "%destinationFile%"
)
IF %F%==0 IF %C%==1 (
::copying a directory c from d, /s: boş olanlar hariç, /e:boş olanlar dahil
xcopy "%sourceCopyDirectory%" "...