subtle ggplot2 techniques

  1. Histograms (geom_histogram) display the count with bars;
    frequency polygons (geom_freqpoly), display the counts with lines.
  2. how to remove extra base line in ggplot2-density plots? (!topic/ggplot2/I3fXMH8foEs) ggplot(a,aes(x=V1))+geom_density() = ggplot(a,aes(x=V1))+geom_line(stat=”density”)

VNC (virtual network computing) server

  1. realVNC
  2. TigerVNC
  3. teamviewer


  1. configure file
  2. foobar

Install Perl and package (local)

Install local Perl

1. download source code

2. ./configure prefix=/path/to/directory

3. make -j 60

4. make -j 60 test

5. make -j 60 install DESTDIR=/path/to/dir

6. setup environment:

Install local packages

7. install local package

JAVA parameters


  1. 查看各种参数默认值:java -XX:+PrintFlagsFinal
  2. -Xmx: Specify the maximum size, in bytes, of the memory allocation pool. (MaxHeapSize)
  3. -Xms: Specify the initial size, in bytes, of the memory allocation pool. (InitialHeapSize)
  4. foobar