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Adding a column to a data.frame
...xt, [[.data.frame.
Data frames can be indexed in several modes. When [ and [[ are used with a single vector index (x[i] or x[[i]]), they index the data frame as if it were a list.
my.dataframe["new.col"] <- a.vector
my.dataframe[["new.col"]] <- a.vector
The data.frame method for $, ...
Check number of arguments passed to a Bash script
...
Just like any other simple command, [ ... ] or test requires spaces between its arguments.
if [ "$#" -ne 1 ]; then
echo "Illegal number of parameters"
fi
Or
if test "$#" -ne 1; then
echo "Illegal number of parameters"
fi
Suggestions
When in Bash,...
O(nlogn) Algorithm - Find three evenly spaced ones within binary string
I had this question on an Algorithms test yesterday, and I can't figure out the answer. It is driving me absolutely crazy, because it was worth about 40 points. I figure that most of the class didn't solve it correctly, because I haven't come up with a solution in the past 24 hours.
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calculating the difference in months between two dates
... figure out a formula for total months difference. Variable days per month and leap years keep throwing me off. How can I get TotalMonths ?
...
Boolean operators && and ||
According to the R language definition , the difference between & and && (correspondingly | and || ) is that the former is vectorized while the latter is not.
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How to iterate over arguments in a Bash script
I have a complex command that I'd like to make a shell/bash script of. I can write it in terms of $1 easily:
8 Answers
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How should I have explained the difference between an Interface and an Abstract class?
...rviews, I have been asked to explain the difference between an Interface and an Abstract class .
30 Answers
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Common programming mistakes for Clojure developers to avoid [closed]
What are some common mistakes made by Clojure developers, and how can we avoid them?
8 Answers
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Call a Server-side Method on a Resource in a RESTful Way
Keep in mind I have a rudimentary understanding of REST. Let's say I have this URL:
8 Answers
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Bomb dropping algorithm
... simple sub-problem.
There are 2 parts to the explanation, the algorithm, and the reason the algorithm
provides an optimal solution. The first won't make sense without the second, so I'll
start with the why.
If you think of bombing the rectangle (assume a big rectangle - no edge cases yet)
you...