J Schreier

The default GUI in Ubuntu20 allows to scale all screens but does not allow separate settings per monitor. To circumvent:
sudo apt-get install gdm3
sudo dpkg-reconfigure gdm3
Note: gdm3 is also not perfect but better than nothing.

Starting Spyder from Python (without conda env)
$python
from spyder.app import start
start.main()

There are enough good manuals on howto install R4 on Ubuntu20, my favorite one is https://www.digitalocean.com/community/tutorials/how-to-install-r-on-ubuntu-20-04-de (in German).

However, if you then install packages, you will likely get failures due to missing libraries.

So what you definitely have to do is
sudo apt install…[Read more]

general discussion: useful command grep MHz /proc/cpuinfo

enabling turbo mode on SuperMicro X10DRi mainboard

First try for Apple (AAPL)
> ohlc = quantmod::getSymbols(“AAPL”, auto.assign = FALSE)
> sd(quantmod::dailyReturn(ohlc))
[1] 0.02033598

So far, so good.
Now try for OPEN (“OPENDOOR TECHNOLOGIES INC”)
> ohlc = quantmod::getSymbols(“OPEN”, auto.assign = FALSE)
> sd(quantmod::dailyReturn(ohlc))
Error in Delt_(getFirst(xx[1]), getLast(xx[ep[2]]), type…[Read more]

In conda env strart R and jupiter as follows
(r4-base) PS C:Usersvasily> RGui (NB RGui or Rscript but not R)
(r4-base) PS C:Usersvasily> jupyter


library(akima)
library(fields)
mhu = aggregate(hu$ret, by=list(hu$sGrow1, hu$sGrow2), FUN=mean)
names(mhu)=c("ret", "sGrow1", "sGrow2")
s <- interp(mhu$ret,mhu$sGrow1,mhu$sGrow2)
image.plot(s)


As I tried to install Java on a Server running under Debian Linux, I broke my source list and got http://ppa.launchpad.net/webupd8team/java/ubuntu/dists/jessie/main/binary-amd64/Packages 404 Not Found by attempts to run sudo apt-get update

Deleting the line http://ppa.launchpad.net/webupd8team/java/ubuntu/dists/jessie/main/binary-amd64/ from…[Read more]

Being an long-time R user I got used to debug my R-Scripts in console (for whatever reasons I rarely use breakpoints in R-Studio). Programming in Python I would of course prefer to have both. It is possible e.g. in PyCharm IDE:
0) set a breakpoint, debug your file
1) switch to console window
2) click on command prompt icon
3) execute arbitrary…[Read more]

Sometimes if you create a dataframe with rbind() in R and then save it by write.table() to a text file, all entries (numeric too) will be put in double quotes.
To remove them one can use the following Python3 script, which is especially useful if you have a lot of files.

import os
filePath = "/path/to/dir"
arr = os.listdir(filePath)
for fileName…[Read more]

To write formulas please use LaTeX. Write [latexpage] before writing a formula.
Example
[latexpage]
$W_t = W_0 \exp{rt}$

will result in
[latexpage]
$W_t = W_0 \exp{rt}$