Installing Ferret on Windows 10

Data from numerical models or observational platforms like satellite are usually gridded and multi-dimensional. With traditional programming languages like Python and Fortran, you need to write a code of about 15-20 lines long to just visualize the data. However, Ferret, which is an interactive visualization and analysis tool who loves handling gridded geographical data, can plot spatial map of a variable along with proper coastlines and land/ocean mask in about 4-6 lines of code. The following code plots the climatological Sea Level Pressure during the month of June.

NOAA/PMEL TMAP
FERRET v7.5 (optimized)
Linux 2.6.32-754.11.1.el6.x86_64 64-bit - 04/25/19
15-Aug-19 13:17
fjnl/ferret.jnl.~4~
yes? use coads_climatology
yes? sh da
currently SET data sets:
1> /home/lijo/ferret/FerretDatasets-7.4/data/coads_climatology.cdf  (default)
name     title                             I         J         K         L
SST      SEA SURFACE TEMPERATURE          1:180     1:90      ...       1:12
AIRT     AIR TEMPERATURE                  1:180     1:90      ...       1:12
SPEH     SPECIFIC HUMIDITY                1:180     1:90      ...       1:12
WSPD     WIND SPEED                       1:180     1:90      ...       1:12
UWND     ZONAL WIND                       1:180     1:90      ...       1:12
VWND     MERIDIONAL WIND                  1:180     1:90      ...       1:12
SLP      SEA LEVEL PRESSURE               1:180     1:90      ...       1:12
yes? fill/l=6 slp
yes? go land 7
yes? go fland  5

Output from above 5 lines of code:

However, Ferret only works in Unix and Mac based systems. So if you are on a Windows machine and want to use Ferret, you are limited to two options: either dual boot your system with a Linux distro like Ubuntu or install a Virtual Machine. Lucky for us, there is now a third and better option, which is to install Ubuntu (or any Unix system) as a Windows app. Bash is now supported in Windows since the roll out of Windows 10 Anniversary update in 2016. They call it Windows Subsystem for Linux (WSL). Once you set-up WSL, you can use almost any Linux supported application like Ferret through the Ubuntu (or any other distro available in Microsoft Store) app.

Here’s a preview:

accessing Ubuntu terminal in Windows 10

Set up WSL and install Ubuntu

Before you begin, make sure your Windows is updated. Also note that this feature only works with 64-bit version of Windows 10. A quick rundown of steps is given here, however, a much more detailed instruction with pictures can be found in How-To Geek’s website.

• Step 1: Navigate to Turn Windows feature on or off option by typing “windows feature” in the start menu.

• Step 2: Scroll down in the new window to find Windows Subsystem for Linux feature and put a tick against it as shown below:

  

• Step 3: Allow your computer to restart.
• Step 4: After the restart open Microsoft Store app and search for “Ubuntu”.

• Step 5: Select the version you want to install and press Get followed by Install.

  Not sure which version to install? Go with the one without any version number. This will install the latest stable version of Ubuntu available.

• Step 6: Once the installation is complete, find the Ubuntu app you just installed in the start menu.

• Step 8: Open the app and follow the instructions. Enter username and password when prompted (you can use any username and password and remember it for later use)

  Note: The password you type won’t be made visible on the screen for security reasons. Keep typing and press enter when done.

• Step 9: Type sudo apt update && sudo apt upgrade in the Ubuntu terminal to install any pending updates for Ubuntu. (sudo commands will ask you to enter a password. Use the same password set in previous step)

Great Job! You now have a working Ubuntu installed as a Windows app. Anytime you need troubleshooting the system, remember to add the keyword WSL to find solutions specific for Ubuntu installed in Windows.

Install Ferret

Now that you have linux in your system, proceed to install Ferret.

• Step 1: Download the Ferret-x.x.x-RHEL7-64.tar.gz (x.x.x corresponds to latest version available at the time) file from Ferret github Release page.
• Step 2: You need to download the ferret_dataset to get coastlines and land/ocean mask working. Bathymetry and standard climatological data like levitus and codas are also included in this dataset. (Choose the latest “source code (tar.gz)” version from the link)

• Step 3: If you closed Ubuntu, open it again by going to the start menu. Make a new directory with name ferret in Ubuntu’s home directory. Move the files you downloaded to this directory and untar them. To do so, you can copy paste the following commands one by one in your Ubuntu terminal.(assuming you downloaded the files to your Windows Downloads folder):

  mkdir ferret
  cd ferret
  mv /mnt/c/Users/your_windows_username/Downloads/Ferret-*-RHEL7-64.tar.gz .
  mv /mnt/c/Users/your_windows_username/Downloads/FerretDatasets*-64.tar.gz .
  tar -xvf Ferret-*-RHEL7-64.tar.gz
  tar -xvf FerretDatasets*.tar.gz
  

  Don’t forget to replace “your_windows_username” with your actual Windows username. If you don’t remember the user name type till mv /mnt/c/Users/ and press the Tab key to find the list of Windows usernames.

  Note: You can access your Windows C drive from Ubuntu by navigating to the path /mnt/c and D drive at /mnt/d and so on. See here for details on file access.

• Step 4: Get the full path to FerretDatasets directory using the command readlink -f FerretDatasets-7.4 and note it down somewhere. You will need it in the next step. (if you have a different dataset version, replace FerretDatasets directory name accordingly)

• Step 5: Change to Ferret’s main directory and start the installation using the commands below:

  # change to ferret's main directory
  cd Ferret**-64
  # start the install process
  ./bin/Finstall
  

• The series of options to be selected are given below:
  • press 2 and then Enter
  • press . and then Enter
  • type the FerretDatasets path you noted in Step 4 and press Enter
  • press . and then Enter
  • press s and then Enter
  • finally press 3 and then Enter to finish and quit installation
  • issue the command source ferret_paths
• That’s it! Check if Ferret is working using the command ./bin/ferret
• If everything went right you should see your prompt change to yes? on the left hand side of your terminal.

• If you get errors like error while loading shared libraries: libreadline.so.6, or error while loading shared libraries: libhistory.so.6, then it is most likely because the library files you have is of different version (like libhistory.so.7 or libreadline.so.7). You can solve this error by linking the library you have to the one which Ferret is expecting. As an example, lets say you got error while loading shared libraries: libreadline.so.6, so you have to do

  # you can check the library path by using "locate libreadline" command
  # For Ubuntu on Windows the path is /lib/x86_64-linux-gnu
  cd /lib/x86_64-linux-gnu
  sudo ln -sf libreadline.so.7 libreadline.so.6
  # come back to the directory you started
  cd - 
  

  check if error is fixed by running ferret again using ./bin/ferret. If a similar error but with different library name appears, repeat the above fix with this new library name.

• You can remove the tar.gz files you downloaded from the ferret directory directory using the following commands

  rm Ferret-*-RHEL7-64.tar.gz
  rm FerretDatasets*.tar.gz
  

• To be able to open Ferret from any folder, place a link to ferret in /usr/local/bin using the following command

  cd /usr/local/bin
  sudo ln -sf ~/ferret/Ferret-*-RHEL7-64/bin/ferret ferret
  

  Add the line source ~/ferret/Ferret-*-RHEL7-64/ferret_paths to your bashrc using vi or vim. If you are not familiar with vi/vim, follow the exact same key combinations as below (remember: if you mess up at anypoint, hold down shift and press z followed by q without releasing shift and retry)

  • type vi ~/.bashrc in your Ubuntu terminal and then press the keys shift+g, then press o, then type source ~/ferret/Ferret-*-RHEL7-64/ferret_paths as it is and press esc key and finally hold down shift key and press z twice. Phew! you are out of vi and your settings have been saved.

Though Ferret is installed and working, the program won’t be able to display anything until a couple of more steps. Right now, Ubuntu can’t spawn any graphical window of its own. You need to install an X server in Windows to serve as an output screen for Ubuntu. So, go ahead and install Xming X server in windows by downloading and running the exe as you would with any other windows software. Once installed, it will launch by default. Mimimize it to system tray so that it keeps running in the background (it’s very light on resource, so consider adding it to your startup applications to avoid the hassle of opening it everytime you start Ubuntu). Try the command go basemap in ferret to check whether display is working. If not, add the line export DISPLAY=:0 to your .bashrc (at the mercy of vi again)

If you made this far, give yourself a pat on the shoulder. It’s all done, happy ferreting.

Bonus

For the folks prefering high quality and premium control of display graphics, try pyferret instead (it is more than just a visual upgrade). It looks and feels the same as Ferret and all your old scripts will still work. Steps to install remain more or less the same as before, expect a few addition steps to install python dependencies. Or by far the easiest method of all, just install it as a conda package right after you set WSL (see this)