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Selecting data frame rows based on partial string match in a column
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mpg cyl disp hp drat wt qsec vs am gear carb
# Merc 240D 24.4 4 146.7 62 3.69 3.19 20.0 1 0 4 2
# Merc 230 22.8 4 140.8 95 3.92 3.15 22.9 1 0 4 2
# Merc 280 19.2 6 167.6 123 3.92 3.44 18.3 1 0 4 4
# Merc 280C 17.8 6 167.6 123 3.92 3.4...
Select Row number in postgres
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answered Aug 14 '12 at 12:29
vyegorovvyegorov
17.8k66 gold badges5050 silver badges7171 bronze badges
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What does the KEY keyword mean?
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edited Sep 4 '19 at 15:19
Yves M.
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Reorder levels of a factor without changing order of values
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Use the levels argument of factor:
df <- data.frame(f = 1:4, g = letters[1:4])
df
# f g
# 1 1 a
# 2 2 b
# 3 3 c
# 4 4 d
levels(df$g)
# [1] "a" "b" "c" "d"
df$g <- factor(df$g, levels = letters[4:1])
# levels(df$g)
# [1] "d" "c" "b" "a"
df
# f g
# 1 1 a
# 2 2 b
# 3 3 c
# 4 ...
How to get execution time in rails console?
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242
timing = Benchmark.measure { Post.all }
The various attributes of the object returned (Benchm...
What is the way to quick-switch between tabs in Xcode 4
I have opened many tabs while working on project. (new feature in Xcode 4).
5 Answers
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Converting of Uri to String
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answered Jun 28 '13 at 2:49
Rico HarisinRico Harisin
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Difference between java.exe and javaw.exe
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4 Answers
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