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Group by multiple columns in dplyr, using string vector input
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data = data.frame(
asihckhdoydkhxiydfgfTgdsx = sample(LETTERS[1:3], 100, replace=TRUE),
a30mvxigxkghc5cdsvxvyv0ja = sample(LETTERS[1:3], 100, replace=TRUE),
value = rnorm(100)
)
# get the columns we want to average within
columns = names(data)[-3]
library(dplyr)
df1 <- data %>%...
Possible reasons for timeout when trying to access EC2 instance
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edited May 12 '10 at 6:00
answered May 11 '10 at 19:55
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How to format strings in Java
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140
In addition to String.format, also take a look java.text.MessageFormat. The format less terse a...
Reducing the space between sections of the UITableView
...15 pixels between every single section I have. I did already try to return 0 for -tableView:heightForFooterInSection: and -tableView:heightForHeaderInSection: but that doesn't change anything.
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How to make blinking/flashing text with CSS 3
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10 Answers
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Two statements next to curly brace in an equation
...cument}
\begin{equation}
f(x)=\begin{cases}
1, & \text{if $x<0$}.\\
0, & \text{otherwise}.
\end{cases}
\end{equation}
\end{document}
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surface plots in matplotlib
...t.figure()
ax = fig.add_subplot(111, projection='3d')
x = y = np.arange(-3.0, 3.0, 0.05)
X, Y = np.meshgrid(x, y)
zs = np.array(fun(np.ravel(X), np.ravel(Y)))
Z = zs.reshape(X.shape)
ax.plot_surface(X, Y, Z)
ax.set_xlabel('X Label')
ax.set_ylabel('Y Label')
ax.set_zlabel('Z Label')
plt.show()
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What is “entropy and information gain”?
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1051
I assume entropy was mentioned in the context of building decision trees.
To illustrate, imag...
How to add a new audio (not mixing) into a video using ffmpeg?
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308
Replace audio
ffmpeg -i video.mp4 -i audio.wav -map 0:v -map 1:a -c:v copy -shortest output.mp...
How can I determine whether a 2D Point is within a Polygon?
...ion, it might translate to something else. On retina screens half a point (0.5/0.5) is pixel. Still, I never noticed that macOS UIs are significantly slower than other UIs. After all 3D APIs (OpenGL or Direct3D) also works with floats and modern graphics libraries very often take advantage of GPU ac...