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sed: print only matching group
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140
Match the whole line, so add a .* at the beginning of your regex. This causes the entire line ...
dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...e .drop argument that does just what you asked for:
df = data.frame(a=rep(1:3,4), b=rep(1:2,6))
df$b = factor(df$b, levels=1:3)
df %>%
group_by(b, .drop=FALSE) %>%
summarise(count_a=length(a))
#> # A tibble: 3 x 2
#> b count_a
#> <fct> <int>
#> 1 1 ...
How to name variables on the fly?
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118
Use assign:
assign(paste("orca", i, sep = ""), list_name[[i]])
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C++ preprocessor __VA_ARGS__ number of arguments
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12 Answers
12
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Transparent ARGB hex value
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edited Feb 18 '16 at 5:17
Robert
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answered Apr 2...
CSS I want a div to be on top of everything
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122
In order for z-index to work, you'll need to give the element a position:absolute or a positio...
Python: fastest way to create a list of n lists
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105
The probably only way which is marginally faster than
d = [[] for x in xrange(n)]
is
from...
In Maven 2, how do I know from which dependency comes a transitive dependency?
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132
To add to @David Crow, here's a dependency:tree example from the Maven site:
mvn dependency:t...
Cartesian product of x and y array points into single array of 2D points
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13 Answers
13
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Abort makefile if variable not set
... all have non-empty values,
# die with an error otherwise.
#
# Params:
# 1. Variable name(s) to test.
# 2. (optional) Error message to print.
check_defined = \
$(strip $(foreach 1,$1, \
$(call __check_defined,$1,$(strip $(value 2)))))
__check_defined = \
$(if $(value $1),, \
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