486. MS data, part IV: Making a stacked spectrum plot using gnuplot

In part 1, I showed you how to export MS data (MS= Mass Spectrometer/ry): http://verahill.blogspot.com.au/2013/07/474-exporting-data-from-wsearch32-and.html

In part 2, I showed you how to generate theoretical isotopic envelopes, and how to compare them with observed ones: http://verahill.blogspot.com.au/2013/07/480-ms-data-part-ii-plotting-and.html

In part 3, I showed you how to make contour plots of '3D' data -- in that particular case the extra dimension was cone voltage, but it could just as easily have been time: http://verahill.blogspot.com.au/2013/07/ms-data-part-iii-generating-matrix-by.html

In part 4, we'll use the same data as in part 3, but we'll make a stacked plot of it. This is a short post.

There is at least one other way of making a stacked plot in gnuplot, but it doesn't yield what I'd consider as being publication quality plots. It's also fairly restrictive in the type of data can be plotted. The method shown here is general and applicable to all types of data. You can e.g. use it for time-dependent NMR data...

Here's an example of a gnuplot script:

### Preamble start
set term png size 1000,500
set output 'stack.png'

set border 1
set xtics nomirror
set ytics nomirror
unset ytics

set xrange [100:3000]
set yrange [0:100]

set multiplot
set size 0.85,0.45
unset key

### Preamble over

### The stacked plot
set origin 0,0
set label "m/z" at 1500, -18
plot '0.dat' with lines lt -1

# we want the x axis to show ONLY for the first spectrum,
# so we turn it off for the remaining spectra.
# The same goes for our label (xlabel can be tricky 
# to position correctly)
unset label
set border 0
unset xtics
unset ytics

# Here we set the spacing (fx) the initial position of the second spectrum (f),
# the initial horizontal offset of the second spectrum relative to the first one (g),
# and the horizontal offset for all subsequent spectra (gy)

f=0.0025
fx=0.00
g=0.01
gy=0.02

# then we plot all the other spectra
set origin fx+0*f,gy+0*g
plot '10.dat' with lines lt -1

set origin fx+1*f,gy+1*g
plot '20.dat' with lines lt -1

set origin fx+2*f,gy+2*g
plot '30.dat' with lines lt -1

set origin fx+3*f,gy+3*g
plot '40.dat' with lines lt -1

set origin fx+4*f,gy+4*g
plot '50.dat' with lines lt -1

set origin fx+5*f,gy+5*g
plot '60.dat' with lines lt -1

set origin fx+6*f,gy+6*g
plot '70.dat' with lines lt -1

set origin fx+7*f,gy+7*g
plot '80.dat' with lines lt -1

set origin fx+8*f,gy+8*g
plot '90.dat' with lines lt -1

set origin fx+9*f,gy+9*g
plot '100.dat' with lines lt -1

set origin fx+10*f,gy+10*g
plot '110.dat' with lines lt -1

set origin fx+11*f,gy+11*g
plot '120.dat' with lines lt -1

set origin fx+12*f,gy+12*g
plot '130.dat' with lines lt -1

set origin fx+13*f,gy+13*g
plot '140.dat' with lines lt -1

set origin fx+14*f,gy+14*g
plot '150.dat' with lines lt -1

set origin fx+15*f,gy+15*g
plot '160.dat' with lines lt -1

set origin fx+16*f,gy+16*g
plot '170.dat' with lines lt -1

set origin fx+17*f,gy+17*g
plot '180.dat' with lines lt -1

set origin fx+18*f,gy+18*g
plot '190.dat' with lines lt -1

set origin fx+19*f,gy+19*g
plot '200.dat' with lines lt -1

set origin fx+20*f,gy+20*g
plot '210.dat' with lines lt -1

set origin fx+21*f,gy+21*g
plot '220.dat' with lines lt -1

set origin fx+22*f,gy+22*g
plot '230.dat' with lines lt -1

set origin fx+23*f,gy+23*g
plot '240.dat' with lines lt -1

set origin fx+24*f,gy+24*g
plot '250.dat' with lines lt -1

set origin fx+25*f,gy+25*g
plot '260.dat' with lines lt -1

set origin fx+26*f,gy+26*g
plot '270.dat' with lines lt -1

set origin fx+27*f,gy+27*g
plot '280.dat' with lines lt -1

set origin fx+28*f,gy+28*g
plot '290.dat' with lines lt -1

set origin fx+29*f,gy+29*g

plot '300.dat' with lines lt -1

and here's the plot:

If you want to make it really fancy, try this:

### Preamble start
set term png size 1000,800
set output 'stack.png'

set border 1
set xtics nomirror
set ytics nomirror
unset ytics

set xrange [100:3000]
set yrange [0:100]

set multiplot
set size 0.85,0.25
unset key

### Preamble over

### The stacked plot
set origin 0,0
set label "m/z" at 1500, -18
plot '0.dat' with lines lt -1

# we want the x axis to show ONLY for the first spectrum,
# so we turn it off for the remaining spectra.
# The same goes for our label (xlabel can be tricky 
# to position correctly)
unset label
set border 0
unset xtics
unset ytics

# Here we set the spacing (fx) the initial position of the second spectrum (f),
# the initial horizontal offset of the second spectrum relative to the first one (g),
# and the horizontal offset for all subsequent spectra (gy)

f=0.0025
fx=0.00
g=0.01
gy=0.02

# then we plot all the other spectra
set origin fx+0*f,gy+0*g
plot '10.dat' with lines lt -1

set origin fx+1*f,gy+1*g
plot '20.dat' with lines lt -1

set origin fx+2*f,gy+2*g
plot '30.dat' with lines lt -1

set origin fx+3*f,gy+3*g
plot '40.dat' with lines lt -1

set origin fx+4*f,gy+4*g
plot '50.dat' with lines lt -1

set origin fx+5*f,gy+5*g
plot '60.dat' with lines lt -1

set origin fx+6*f,gy+6*g
plot '70.dat' with lines lt -1

set origin fx+7*f,gy+7*g
plot '80.dat' with lines lt -1

set origin fx+8*f,gy+8*g
plot '90.dat' with lines lt -1

set origin fx+9*f,gy+9*g
plot '100.dat' with lines lt -1

set origin fx+10*f,gy+10*g
plot '110.dat' with lines lt -1

set origin fx+11*f,gy+11*g
plot '120.dat' with lines lt -1

set origin fx+12*f,gy+12*g
plot '130.dat' with lines lt -1

set origin fx+13*f,gy+13*g
plot '140.dat' with lines lt -1

set origin fx+14*f,gy+14*g
plot '150.dat' with lines lt -1

set origin fx+15*f,gy+15*g
plot '160.dat' with lines lt -1

set origin fx+16*f,gy+16*g
plot '170.dat' with lines lt -1

set origin fx+17*f,gy+17*g
plot '180.dat' with lines lt -1

set origin fx+18*f,gy+18*g
plot '190.dat' with lines lt -1

set origin fx+19*f,gy+19*g
plot '200.dat' with lines lt -1

set origin fx+20*f,gy+20*g
plot '210.dat' with lines lt -1

set origin fx+21*f,gy+21*g
plot '220.dat' with lines lt -1

set origin fx+22*f,gy+22*g
plot '230.dat' with lines lt -1

set origin fx+23*f,gy+23*g
plot '240.dat' with lines lt -1

set origin fx+24*f,gy+24*g
plot '250.dat' with lines lt -1

set origin fx+25*f,gy+25*g
plot '260.dat' with lines lt -1

set origin fx+26*f,gy+26*g
plot '270.dat' with lines lt -1

set origin fx+27*f,gy+27*g
plot '280.dat' with lines lt -1

set origin fx+28*f,gy+28*g
plot '290.dat' with lines lt -1

set origin fx+29*f,gy+29*g

plot '300.dat' with lines lt -1

### second plot
set size 0.75,0.4
set origin 0.1,0.6
set xrange [800:1800]
set border 3
set xtics nomirror
set ytics nomirror
set xlabel 'm/z'
set ylabel 'Relative abundance (%)'
set title '20 V'

plot '20.dat' with lines lt -1

unset multiplot

which looks like this:

477. OpenChrom - Dempster

I don't want to get into writing software reviews, but given how much OpenChrom, an open source program for mass spectrometry which can open a range of proprietary formats, has evolved since I tried the release code-named Syringe (http://verahill.blogspot.com.au/2012/09/using-openchrom-to-open-aglient-d-esi.html) in September 2012, I think a brief update may be in order.

Essentially, OpenChrom now seems a lot easier and more natural to use.

The installation is the same as before (I've copied the old post below):

---

1. Install Java v1.7 (need > 1.6)
You can either use openjdk 7 or (Oracle) Java. See here for a general guide to installing Oracle/Sun Java.

As for openjdk, you can easily install it:
sudo apt-get install openjdk-7-jdk

(the openjdk-7-jre package is enough if you don't want the full developer's kit)

Anyway.

Make sure that you've selected the right version:

 sudo update-alternatives --config java
There are 7 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
  0            /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java   1061      auto mode
  1            /usr/bin/gij-4.4                                 1044      manual mode
  2            /usr/bin/gij-4.6                                 1046      manual mode
  3            /usr/bin/gij-4.7                                 1047      manual mode
  4            /usr/lib/jvm/j2re1.6-oracle/bin/java             314       manual mode
  5            /usr/lib/jvm/j2sdk1.6-oracle/jre/bin/java        315       manual mode
  6            /usr/lib/jvm/java-6-openjdk-amd64/jre/bin/java   1061      manual mode
 *7            /usr/lib/jvm/java-7-openjdk-amd64/jre/bin/java   1051      manual mode

---

2. Get openchrom

cd ~/tmp

wget http://aarnet.dl.sourceforge.net/project/openchrom/REL-0.8.0-PREV/openchrom_linux.gtk.x86_64_0.8.0-PREV.zip

unzip openchrom_linux.gtk.x86_64_0.6.0.zip

cd linux.gtk.x86_64/OpenChrom/

sudo mkdir /opt/openchrom

sudo chown $USER /opt/openchrom 

cp * -R /opt/openchrom

chmod +x /opt/openchrom/openchrom

Stick

alias openchrom='/opt/openchrom/openchrom'

in your ~/.bashrc and source it.

---

A few notes:
You can now start OpenChrom by running

openchrom

from the command line.

You can install plug-ins, e.g. to open Agilent files, by going to Plugins/OpenChrom Marketplace. Plugins will typically run for 30 days, but can be unlocked for perpetuity by adding a serial key, which is free. Add license keys by first registering on the openchrom website, going to http://www.openchrom.net/main/content/plugins.php, and clicking on the plugin you want a serial key for. You can then enter that key by going e.g. Window/Preferences/Converter in the OpenChrom software.

Everyone has their own idea of what a good piece of mass spec software should look like, and I suspect that OpenChrom caters to them all. Layouts are called Perspectives here. On the flip side, if you accidentally use a perspective that doesn't suit you, you may be incredibly frustrated until you figure out what's going on.

I like wsearch32, so my preferred view is to go to Window/Perspective Switcher -> Chromatogram MS (exact).

Opening spectra is much easier than before: now simply go to File/Open Chromatogram (MSD) and click on the file (or directory structure in the case of e.g. Agilent .D directories) and open:

Anyway, openchrom is getting better, is easier to use, and is still the only open source program that I know which can handle such an array of proprietary formats. Also, it can export data in both .csv and .xls formats, but you will need to install plugins for that, which is luckily very simple.