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How to check if a string array contains one string in JavaScript? [duplicate]
I have a string array and one string. I'd like to test this string against the array values and apply a condition the result - if the array contains the string do "A", else do "B".
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Assign multiple columns using := in data.table, by group
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Thanks for this answer and the examples. How should I modify the following line in order to get two columns for each objectName from the dim output, rather than one column with two rows? data.table(objectName=ls())[,c("rows","cols"):=dim(get(objec...
dplyr: “Error in n(): function should not be called directly”
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I presume you have dplyr and plyr loaded in the same session. dplyr is not plyr. ddply is not a function in the dplyr package.
Both dplyr and plyr have the functions summarise/summarize.
Look at the results of conflicts() to see masked objects.
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What is the difference between class and instance methods?
What's the difference between a class method and an instance method?
18 Answers
18
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C++ const map element access
...ut_of_range exception. (This is similar to the behaviour of at() for deque and vector.)
Because of this behaviour it makes sense for there to be a const overload of at(), unlike operator[] which always has the potential to change the map.
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What is x after “x = x++”?
...gning the old value of x back into itself.
x = x++;
x++ increments x and returns its old value.
x = assigns the old value back to itself.
So in the end, x gets assigned back to its initial value.
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How to format strings using printf() to get equal length in the output?
...o functions, one which produces messages like Starting initialization... and another which checks return codes and outputs "Ok" , "Warning" or "Error" . However, the output that is produced is of the different length:
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How to add a changed file to an older (not last) commit in Git
I have changed several things over the last hour and committed them step by step, but I just realized I've forgot to add a changed file some commits ago.
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How to add “on delete cascade” constraints?
... You have to drop the constraint first, then add the correct version. In standard SQL, I believe the easiest way to do this is to
start a transaction,
drop the foreign key,
add a foreign key with on delete cascade, and finally
commit the transaction
Repeat for each foreign key you want to change...
What is the difference between git clone and checkout?
What is the difference between git clone and git checkout ?
5 Answers
5
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