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What does “@@ -1 +1 @@” mean in Git's diff output?
...to-file to-file-modification-time
The time stamp looks like 2002-02-21 23:30:39.942229878 -0800 to indicate the date, time with fractional seconds, and time zone. The fractional seconds are omitted on hosts that do not support fractional time stamps.
You can change the header's content wi...
Passing command line arguments to R CMD BATCH
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115
My impression is that R CMD BATCH is a bit of a relict. In any case, the more recent Rscript e...
Mean per group in a data.frame [duplicate]
...aggregate was designed for:
d <- read.table(text=
'Name Month Rate1 Rate2
Aira 1 12 23
Aira 2 18 73
Aira 3 19 45
Ben 1 53 19
Ben 2 22 87
Ben 3 19 45
Cat 1 22 ...
how to change default python version?
...onfusing that when I type python -V in Terminal it says that Python 2.6.1 , how can I change the default python version?
...
In Matlab, when is it optimal to use bsxfun?
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152
+500
There ...
Bubble Sort Homework
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127
To explain why your script isn't working right now, I'll rename the variable unsorted to sorte...
Ruby: What is the easiest way to remove the first element from an array?
...
11 Answers
11
Active
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How to write a bash script that takes optional input arguments?
...
You could use the default-value syntax:
somecommand ${1:-foo}
The above will, as described in Bash Reference Manual - 3.5.3 Shell Parameter Expansion [emphasis mine]:
If parameter is unset or null, the expansion of word is substituted. Otherwise, the value of parameter is ...
Python creating a dictionary of lists
...s import defaultdict
>>> d = defaultdict(list)
>>> a = ['1', '2']
>>> for i in a:
... for j in range(int(i), int(i) + 2):
... d[j].append(i)
...
>>> d
defaultdict(<type 'list'>, {1: ['1'], 2: ['1', '2'], 3: ['2']})
>>> d.items()
[(1, ['1']), (...