Merge pull request #81 from jieunyoo/master

edits to address issue #74. syntax changed to directly access file instead of copying file to container, screenshot included

docs/analysis/datasim/mcsimulations.md

@@ -39,3 +39,46 @@ briefly describes the steps in the MC production chain.
 The data format in use for Run1 MC data is Analysis Object Data (AODSIM). Starting from Run2, a slimmer version of this format called MINIAODSIM is used.
 A brief description of data formats can be found in the
 introductory [About CMS](http://opendata.cern.ch/docs/about-cms) under "*Primary and simulated datasets*".
+
+## Cross section calculation
+
+Cross sections can be calculated for MC samples.
+
+Caveat: The cross-sections found with this tool are those predicted by the respective generators. There may be better estimates, coming from dedicated task forces, theory papers etc.
+
+To account for the different running conditions in Run 1 vs Run 2, click the appropriate tab below for Run 1 vs Run 2 data.
+
+=== "Run 1 Data"
+
+    * This page is under construction
+
+=== "Run 2 Data"
+
+    * You can calculate a cross section using the GenXSecAnalyzer. To use it, you will need the file ana.py, which you can get by `curl https://raw.githubusercontent.com/cms-sw/genproductions/master/Utilities/calculateXSectionAndFilterEfficiency/genXsec_cfg.py -o ana.py `
+
+    * Next, fetch a CMSSW image and start a container. You can find a list of Docker container images available for CMS open data in the [guide page for CMS open data containers](http://opendata.cern.ch/docs/cms-guide-docker). A tutorial on working with docker is at [CMS open data containers](https://cms-opendata-workshop.github.io/workshop2022-lesson-docker/). If you named your container my_ord, you can fetch and start it by
+
+    ``` bash
+
+    docker run --name my_od -P -p 5901:5901 -it cmsopendata/cmssw_7_6_7-slc6_amd64_gcc493 /bin/bash
+
+    cd CMSSW_7_6_7/src
+
+    cmsenv
+
+    ```
+
+    * Then, copy the file ana.py to your container. You would also copy any root file/s you need to your container.
+
+    * Finally, to compute the cross-section, type `cmsRun ana.py inputFiles="file:xxxx.root" maxEvents=-1` Note that you must use the syntax "file:" before your root file name. For example, if your root file is called ttbar.root, you would type `cmsRun ana.py inputFiles="file:ttbar.root" maxEvents=-1`
+
+    * After running the above commands, you will get a log file.
+
+    * A cross-section summary will be printed out. The definition of each quantity is:
+
+        * Before matching: the cross section before jet matching and any filter
+        * After matching: the cross section after jet matching BUT before any filter
+        * Filter efficiency: the efficiency of the any filter.
+        * After filter: the cross section after jet matching and additional filter are applied. This is your final cross section.
+
+    * A file you can use for testing is 1A454199-F8B8-E511-A55D-7845C4FC374C.root from [Simulated dataset TGJets_TuneCUETP8M1_13TeV_amcatnlo_madspin_pythia8 in MINIAODSIM format for 2015 collision data](http://opendata.cern.ch/record/19924).

mkdocs.yml

@@ -82,8 +82,7 @@ nav:
                  - 'Tagging uncertainties': analysis/systematics/objectsuncertain/btaguncertain.md
             - 'Pileup Uncertainty': analysis/systematics/pileupuncertain.md
         - 'Interpretation':
-            - 'Statistics': analysis/interpretation/stats.md
-            - 'Cross Sections': analysis/interpretation/crossSections.md
+            - 'Statistics': analysis/interpretation/stats.md  
             - 'Upper-limit Calculations': analysis/interpretation/limits.md
     - FAQ: faq.md
     - About: about.md