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How to use a variable to specify column name in ggplot
...t will remain around for a long time).
The idiomatic way now would be to convert to a symbol the string that the variable contains, using sym()(which is almost the same as base aliases as.name() / as.symbol()), and unquote it using !!
Simulating OP's data we can do :
library(tidyverse)
rates.by....
Can I set background image and opacity in the same property?
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Two methods:
Convert to PNG and make the original image 0.2 opacity
(Better method) have a <div> that is position: absolute; before #main and the same height as #main, then apply the background-image and opacity: 0.2; filter: alph...
n-grams in python, four, five, six grams?
...o use the nltk.word_tokenize() function. Also to print the results had to convert the generator object like bigrams, trigrams and fourgrams to list using list(<genrator_object>).
– bhatman
Dec 18 '18 at 5:00
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What does the thread_local mean in C++11?
I am confused with the description of thread_local in C++11. My understanding is, each thread has unique copy of local variables in a function. The global/static variables can be accessed by all the threads (possibly synchronized access using locks). And the thread_local variables are visible to...
Object-orientation in C
...It tries to keep minimal the available concepts for the sake of simplicity and flexibility: uniform object oriented programming including open classes, metaclasses, property metaclasses, generics, multimethods, delegation, ownership, exceptions, contracts and closures. There is a draft paper (PDF) ...
Java - sending HTTP parameters via POST method easily
...;param2=b&param3=c";
byte[] postData = urlParameters.getBytes( StandardCharsets.UTF_8 );
int postDataLength = postData.length;
String request = "http://example.com/index.php";
URL url = new URL( request );
HttpURLConnection conn= (HttpURLConnection) url.openConnecti...
Simple (non-secure) hash function for JavaScript? [duplicate]
... hash = ((hash<<5)-hash)+char;
hash = hash & hash; // Convert to 32bit integer
}
return hash;
}
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Display image as grayscale using matplotlib
...s plt
from PIL import Image
fname = 'image.png'
image = Image.open(fname).convert("L")
arr = np.asarray(image)
plt.imshow(arr, cmap='gray', vmin=0, vmax=255)
plt.show()
If you want to display the inverse grayscale, switch the cmap to cmap='gray_r'.
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C++ mark as deprecated
...for this all I got was a Microsoft specific solution; #pragma deprecated and __declspec(deprecated) .
7 Answers
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Is char signed or unsigned by default?
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The book is wrong. The standard does not specify if plain char is signed or unsigned.
In fact, the standard defines three distinct types: char, signed char, and unsigned char. If you #include <limits.h> and then look at CHAR_MIN, you can find...