For this tutorial I am going to assume that you have some idea about using either Jupyter notebook or Python in general. I also assume that you have Anaconda installed, or know how to install packages into Python. If you do not, then I would first suggest putting a few minutes aside for installing Anaconda and taking a crash course in Jupyter.
The data structure
I am breaking down the data that I’m going to work with because the things I’m going to talk in this post can be applied to any other data which looks similar – That is, a simple two column data, which when plotted will form a 2D line plot with an x and y-axis.
In my lab we use a spectrometer to collect data. For the uninitiated, a spectrometer is basically a fancy prism with a camera at the rainbow end to take a black and white picture (intensity) of the rainbow. The data in this case is formed by spatially dispersing an input light into its constituent colors (wavelengths of that color). The intensity for each color is recorded using a camera. That is two columns of data – Wavelength is the first column, in nanometers and Intensity is the second column (photon counts, let’s say). The data file, of a near-infrared spectrum around 900 nm, if opened in a text editor, would look as follows.
900.0999819 1072801 900.200739 1087873 900.3014958 1101660 900.4022521 1113931 900.5030081 1118967 900.6037637 1099496 900.704519 1097624 900.8052738 1113681
If you would like to use the same data file I am using, you can download it from here.
Now, note that ASCII files like these are easier to handle for us starters and should show good numbers when opened using notepad or Microsoft excel.
Other proprietary formats such as the ones that directly come out of our spectrometer, like .SPE formats (for Princeton instruments cameras) is a binary format. These will give you garbage if you try to open these with notepad or excel. There is a way to open these using Python, but you need to have a detailed information about the format and construct the code accordingly to read them properly. In this post I’m going to deal with simpler ASCII (text, CSV files etc) files only.
If you are dealing with SPE or other such difficult file formats, I would suggest using a file conversion software that usually comes with the equipment to export the binary file to txt or csv format.Continue reading Reading and plotting data in Jupyter notebook