Java replaceAll / replace string with instances of dollar sign
String replace method is not replacing characters
"In" vs. "after" for future talk Uniform convergence of derivatives, Tao 14.2.7. I am having a problem computing the pearson correlation coefficient of data sets with possibly zero standard deviation (i.e. all data has the same value).  Suppose that I have the following two data sets:  float x[] = {2, 2, 2, 3, 2}; float y[] = {2, 2, 2, 2, 2};   The correlation coefficient "r", would be computed using the following equation:  float r = covariance(x, y) / (std_dev(x) * std_dev(y));   However, because all data in data set "y" has the same value, the standard deviation std_dev(y) would be zero and "r" would be undefined.  Is there any solution for this problem? Or should I use other methods to measure data relationship in this case? Comparing two logit or probit curves using a single parameter I've conducted a psychological experiment on the same subject, under two different condition. For each condition I've collected the number of correct and wrong answer for each stimulus (number of trials per stimulus = 10; number of stimulus = 15). From the data collected I fitted a psychometric curve (probit or logit curve), and now I want to compare the results.  Consider subject 1: His answers are collected in the following matrices  **COND_1**     correct cnt   Y  N   1   0 10   2   0 10   3   0 10   4   0 10   5   0 10   6   0 10   7   1  9   8   4  6   9   5  5   10  7  3   11  8  2   12  7  3   13 10  0   14 10  0   15 10  0  **COND_2**     correct cnt   Y  N   1   0 10   2   2  8   3   2  8   4   3  7   5   2  8   6   4  6   7   8  2   8  10  0   9   8  2   10 10  0   11  9  1   12 10  0   13 10  0   14 10  0   15 10  0  COND_1.1 &lt;- matrix(c(0, 2, 2, 3, 2, 4, 8, 10, 8, 10, 9, 10, 10, 10, 10, 10, 8, 8, 7, 8, 6, 2, 0, 2, 0, 1, 0, 0, 0, 0), byrow=F, ncol=2)  COND_1.2 &lt;- matrix(c(0, 0, 0, 0, 0, 0, 1, 4, 5, 7, 8, 7, 10, 10, 10, 10, 10, 10, 10, 10, 10, 9, 6, 5, 3, 2, 3, 0, 0, 0), byrow=F, ncol=2)  cnt &lt;- seq(from=0, to=1.4, by=0.1)  ddprob.1.1 &lt;- glm(COND_1.1 ~ cnt, family = binomial(link = "probit"))  ddprob.2.1 &lt;- glm(COND_2.1 ~ cnt, family = binomial(link = "probit"))     Observing the plot, you can surely say that performance under condition 2 is better then the performance under condition 1. In fact if you compute some parameters like AUC, p25, p50, p75 (the value of the stimulus at which the number of correct answers are 25%, 50% and 75% each) [threshold parameters], you'll see that:  COND_1      COND_2 AUC    &lt;    AUC p25    &gt;    p25 p50    &gt;    p50 p75    &gt;    p75     Now consider subject 2:  COND_1     correct cnt   Y  N   1   0 10   2   0 10   3   0 10   4   0 10   5   3  7   6   3  7   7   4  6   8   5  5   9   9  1   10  9  1   11 10  0   12 10  0   13 10  0   14 10  0   15 10  0  COND_2     correct cnt   Y  N   1   0 10   2   1  9   3   0 10   4   4  6   5   2  8   6   6  4   7   4  6   8   7  3   9   4  6   10  7  3   11  7  3   12 10  0   13  9  1   14 10  0   15 10  0   COND_1.2 &lt;- matrix(c(0, 0, 0, 0, 3, 3, 4, 5, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 7, 7, 6, 5, 1, 1, 0, 0, 0, 0, 0), byrow=F, ncol=2) COND_2.2 &lt;- matrix(c(0, 1, 0, 4, 2, 6, 4, 7, 4, 7, 7, 10, 9, 10, 10, 10, 9, 10, 6, 8, 4, 6, 3, 6, 3, 3, 0, 1, 0, 0), byrow=F, ncol=2) cnt &lt;- seq(from=0, to=1.4, by=0.1)  ddprob.1.1 &lt;- glm(COND_1.2 ~ cnt, family = binomial(link = "probit")) ddprob.2.1 &lt;- glm(COND_2.2 ~ cnt, family = binomial(link = "probit"))   The plotted curves are shown in the image below.    Can you say what performance is better? Under condition 1 or under condition 2? Extrapolating AUC, p25, p50, p75, you have:  COND_1      COND_2 AUC     &gt;   AUC p25     &gt;   p25 p50     =   p50 p75     &lt;   p75   So my question is: Is there a method to say that a generic curve (logit, probit or whatelse) is HIGHER then another? Is there a method to compare (a single number of "performance") that describe the differences of the two curves? My example shows that AUC, p25, p50, p75 are not good parameters. I'd like to compute a single numeric parameter for each curves, to make a simple t-paired test, extrapolated from the distribution seen. How do I escape the wildcard/asterisk character in bash? For example:  me$ FOO="BAR * BAR" me$ echo $FOO BAR file1 file2 file3 file4 BAR   and using the \ escape character:  me$ FOO="BAR \* BAR" me$ echo $FOO BAR \* BAR   I'm obviously doing something stupid.  How do I get the output BAR * BAR? How to attach my repo to heroku app This may be a silly question, and I think I have looked elsewhere to find the answer...  Might be a path issue, but when I open the command line and type from the C:\&gt;: cd D:\  I cannot get to the D drive.  Even if I type: cd D:\&lt;folder name&gt;  The command.exe will auto-complete the line with the tab key, so it knows where I'm at.  It just doesn't print to screen the result or actually get me there.  This problem exists for the network drives as well. Now, if I use the chdir (cd) command like this: chdir D: or cd d: I get the print out of the D:\ below the command but it still says I'm in the C:\. I feel like I'm missing something simple. How to prove Euler's formula: $e^{i\varphi}=\cos(\varphi) +i\sin(\varphi)$? Could you provide a proof of Euler's formula: $e^{i\varphi}=\cos(\varphi) +i\sin(\varphi)$? I would like to convert a Mp4 file in HD into a Mp4 file of lower resolution. Is there any software that can be used for this? How do you find all subclasses of a given class in Java? How does one go about and try to find all subclasses of a given class (or all implementors of a given interface) in Java? As of now, I have a method to do this, but I find it quite inefficient (to say the least). The method is:    Get a list of all class names that exist on the class path Load each class and test to see if it is a subclass or implementor of the desired class or interface   In Eclipse, there is a nice feature called the Type Hierarchy that manages to show this quite efficiently. How does one go about and do it programmatically? What is the right ffmpeg output format for a v4l2-loopback device? Following the guide in  I did:  $ sudo modprobe v4l2loopback $ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0   The device /dev/video0 shows up as expected but the ffmpeg command fails with following output:  $ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f v4l2 /dev/video0 ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers ... [x11grab @ 0x559767794cc0] Stream #0: not enough frames to estimate rate; consider increasing probesize .... [v4l2 @ 0x55976779e6c0] ioctl(VIDIOC_G_FMT): Invalid argument Could not write header for output file #0 (incorrect codec parameters ?): Invalid argument Error initializing output stream 0:0 --  Conversion failed!   I already tried to follow the suggestions below the answer to no avail. I noticed that v4l2 is listed as demux only in ffmpeg -formats. Does that mean I can't use it for output to /dev/video0? If so, what should I use instead? I tried h264 but that crashes after ~1000 frames with following error message:  $ ffmpeg -f x11grab -r 15 -s 1280x720 -i :0.0+0,0 -vcodec rawvideo -pix_fmt yuv420p -threads 0 -f h264 /dev/video0 ffmpeg version 4.0 Copyright (c) 2000-2018 the FFmpeg developers ... [x11grab @ 0x55da61e29cc0] Stream #0: not enough frames to estimate rate; consider increasing probesize ... File '/dev/video0' already exists. Overwrite ? [y/N] y .... Error writing trailer of /dev/video0: Invalid argument .... Conversion failed! How to find and delete identical points? I recently performed  on a merged point feature class in ArcGIS 10.1.  I specified "1 meter" XY tolerance for the Integrate command.  The resulting point feature appears to be what I want except points that were integrated are now stacked on top of each other, which will be problematic in future processing steps.  The attributes for my dataset consist of an OID, Shape, x, y, z.  Where x and y = UTM coordinates and z = buffer distance.  The command  does not appear to work for my dataset (i.e based on Fields: OID, Shape, x, y, z and XY tolerance = 1m) as the output still has stacked points.  I am also working with big data--the integrate output has 37 million points.    There is a related thread, titled , although I would like to open the question up to python solutions too.  What is the best way to find and delete (spatially) duplicate points?  Is there a better solution to integrating such that the output does not contain overlapping points? Java: Prefix/postfix of increment/decrement operators? What's the difference between $\equiv$ and $\leftrightarrow$ in a formal proof? Is there a system in place to prevent new users asking, answering and accepting answers to each others' off-topic questions? Show that the series $\sum\limits_{n=2}^{\infty} \frac {(n^3+1)^{1/3}-n}{\log n}$ converges How can I tell what year my bike was made? Math mode accents In my long document I, sadly, have to use several accents to denote different kinds of symbols. Currently, I use primes ($x'$), hat, tilde, and overline. In addition I use two colored symbols (red colored tilde and blue $\prescript\ulcorner$), as I need further distinguishment.  Now I'd like to have no colors in my document, while I still have at least six different ways to differentiate certain symbols.  Which alternatives could I use that are easy to recognize and 'stand out', while they are different to prime/hat/tilde/overline?  EDIT: The reader should be able to see the kind of accent used even if the symbol in question is in a sub-script (possibly even a sub-sub-script). Prove that $\left (\frac{a^2 + b^2 +c^2}{a+b+c} \right) ^ {(a+b+c)} > a^a b^b c^c$ Prove that $\left (\dfrac{a^2 + b^2 +c^2}{a+b+c} \right) ^ {(a+b+c)} &gt; a^a b^b c^c$ if $a$, $b$ and $c$ are distinct natural numbers.  Is it possible using induction? How do I Parameterize a null string with DBNull.Value clearly and quickly