From fd7f12e9d95891291e586c7f0d6cab7d37833068 Mon Sep 17 00:00:00 2001
From: 1d334d5105a1a432e18f2e361780bab5
 <1d334d5105a1a432e18f2e361780bab5@app-learninglab.inria.fr>
Date: Sat, 7 May 2022 12:50:00 +0000
Subject: [PATCH] analyze completed

---
 module2/exo4/exercice.ipynb | 635 +++---------------------------------
 1 file changed, 39 insertions(+), 596 deletions(-)

diff --git a/module2/exo4/exercice.ipynb b/module2/exo4/exercice.ipynb
index 4b30ef0..b808b9b 100644
--- a/module2/exo4/exercice.ipynb
+++ b/module2/exo4/exercice.ipynb
@@ -11,610 +11,39 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "# Data import"
+    "We want to analyze how the nitrogen fertilizer price per ton evolved with years."
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "This data gives the long-term evolution of nitrogen fertilizer price in USD"
+    "# Data import"
    ]
   },
   {
-   "cell_type": "code",
-   "execution_count": 1,
+   "cell_type": "markdown",
    "metadata": {},
-   "outputs": [
-    {
-     "name": "stdout",
-     "output_type": "stream",
-     "text": [
-      "DATE,PCU325311325311\n",
-      "1975-12-01,88.1\n",
-      "1976-01-01,87.6\n",
-      "1976-02-01,85.0\n",
-      "1976-03-01,84.8\n",
-      "1976-04-01,84.7\n",
-      "1976-05-01,84.6\n",
-      "1976-06-01,83.5\n",
-      "1976-07-01,83.0\n",
-      "1976-08-01,83.2\n",
-      "1976-09-01,83.1\n",
-      "1976-10-01,83.5\n",
-      "1976-11-01,83.2\n",
-      "1976-12-01,83.0\n",
-      "1977-01-01,82.5\n",
-      "1977-02-01,84.5\n",
-      "1977-03-01,86.9\n",
-      "1977-04-01,87.6\n",
-      "1977-05-01,87.4\n",
-      "1977-06-01,87.1\n",
-      "1977-07-01,87.2\n",
-      "1977-08-01,87.1\n",
-      "1977-09-01,87.2\n",
-      "1977-10-01,86.4\n",
-      "1977-11-01,84.6\n",
-      "1977-12-01,83.9\n",
-      "1978-01-01,83.3\n",
-      "1978-02-01,85.0\n",
-      "1978-03-01,86.6\n",
-      "1978-04-01,86.7\n",
-      "1978-05-01,86.1\n",
-      "1978-06-01,85.7\n",
-      "1978-07-01,85.2\n",
-      "1978-08-01,84.5\n",
-      "1978-09-01,84.5\n",
-      "1978-10-01,85.5\n",
-      "1978-11-01,84.2\n",
-      "1978-12-01,83.9\n",
-      "1979-01-01,84.0\n",
-      "1979-02-01,85.1\n",
-      "1979-03-01,86.4\n",
-      "1979-04-01,89.4\n",
-      "1979-05-01,89.8\n",
-      "1979-06-01,89.3\n",
-      "1979-07-01,90.6\n",
-      "1979-08-01,91.7\n",
-      "1979-09-01,93.4\n",
-      "1979-10-01,95.1\n",
-      "1979-11-01,98.4\n",
-      "1979-12-01,100.0\n",
-      "1980-01-01,.\n",
-      "1980-02-01,.\n",
-      "1980-03-01,.\n",
-      "1980-04-01,.\n",
-      "1980-05-01,.\n",
-      "1980-06-01,.\n",
-      "1980-07-01,.\n",
-      "1980-08-01,.\n",
-      "1980-09-01,.\n",
-      "1980-10-01,.\n",
-      "1980-11-01,.\n",
-      "1980-12-01,116.1\n",
-      "1981-01-01,118.9\n",
-      "1981-02-01,121.6\n",
-      "1981-03-01,124.9\n",
-      "1981-04-01,129.6\n",
-      "1981-05-01,130.8\n",
-      "1981-06-01,126.4\n",
-      "1981-07-01,126.4\n",
-      "1981-08-01,126.8\n",
-      "1981-09-01,125.2\n",
-      "1981-10-01,125.9\n",
-      "1981-11-01,127.0\n",
-      "1981-12-01,125.9\n",
-      "1982-01-01,125.4\n",
-      "1982-02-01,125.7\n",
-      "1982-03-01,125.3\n",
-      "1982-04-01,124.8\n",
-      "1982-05-01,123.7\n",
-      "1982-06-01,122.9\n",
-      "1982-07-01,119.7\n",
-      "1982-08-01,119.7\n",
-      "1982-09-01,119.2\n",
-      "1982-10-01,120.5\n",
-      "1982-11-01,118.4\n",
-      "1982-12-01,117.5\n",
-      "1983-01-01,117.0\n",
-      "1983-02-01,116.6\n",
-      "1983-03-01,116.4\n",
-      "1983-04-01,116.6\n",
-      "1983-05-01,116.0\n",
-      "1983-06-01,115.4\n",
-      "1983-07-01,114.9\n",
-      "1983-08-01,114.0\n",
-      "1983-09-01,111.7\n",
-      "1983-10-01,111.7\n",
-      "1983-11-01,113.2\n",
-      "1983-12-01,114.9\n",
-      "1984-01-01,116.7\n",
-      "1984-02-01,121.3\n",
-      "1984-03-01,126.1\n",
-      "1984-04-01,127.6\n",
-      "1984-05-01,127.8\n",
-      "1984-06-01,127.1\n",
-      "1984-07-01,126.0\n",
-      "1984-08-01,122.6\n",
-      "1984-09-01,122.0\n",
-      "1984-10-01,122.7\n",
-      "1984-11-01,121.1\n",
-      "1984-12-01,121.2\n",
-      "1985-01-01,122.0\n",
-      "1985-02-01,123.1\n",
-      "1985-03-01,123.0\n",
-      "1985-04-01,123.7\n",
-      "1985-05-01,123.3\n",
-      "1985-06-01,122.6\n",
-      "1985-07-01,122.4\n",
-      "1985-08-01,121.1\n",
-      "1985-09-01,123.8\n",
-      "1985-10-01,122.2\n",
-      "1985-11-01,121.8\n",
-      "1985-12-01,119.6\n",
-      "1986-01-01,114.5\n",
-      "1986-02-01,114.6\n",
-      "1986-03-01,115.3\n",
-      "1986-04-01,114.3\n",
-      "1986-05-01,114.3\n",
-      "1986-06-01,114.1\n",
-      "1986-07-01,108.7\n",
-      "1986-08-01,103.8\n",
-      "1986-09-01,102.5\n",
-      "1986-10-01,99.6\n",
-      "1986-11-01,99.1\n",
-      "1986-12-01,99.7\n",
-      "1987-01-01,97.5\n",
-      "1987-02-01,102.1\n",
-      "1987-03-01,106.2\n",
-      "1987-04-01,108.9\n",
-      "1987-05-01,105.9\n",
-      "1987-06-01,104.7\n",
-      "1987-07-01,103.8\n",
-      "1987-08-01,103.7\n",
-      "1987-09-01,102.7\n",
-      "1987-10-01,101.7\n",
-      "1987-11-01,103.2\n",
-      "1987-12-01,105.3\n",
-      "1988-01-01,110.4\n",
-      "1988-02-01,117.3\n",
-      "1988-03-01,120.4\n",
-      "1988-04-01,120.3\n",
-      "1988-05-01,119.0\n",
-      "1988-06-01,115.2\n",
-      "1988-07-01,116.8\n",
-      "1988-08-01,117.2\n",
-      "1988-09-01,119.3\n",
-      "1988-10-01,122.9\n",
-      "1988-11-01,127.1\n",
-      "1988-12-01,131.4\n",
-      "1989-01-01,133.5\n",
-      "1989-02-01,134.9\n",
-      "1989-03-01,136.4\n",
-      "1989-04-01,133.9\n",
-      "1989-05-01,130.8\n",
-      "1989-06-01,121.4\n",
-      "1989-07-01,113.0\n",
-      "1989-08-01,110.2\n",
-      "1989-09-01,107.6\n",
-      "1989-10-01,106.7\n",
-      "1989-11-01,108.7\n",
-      "1989-12-01,112.3\n",
-      "1990-01-01,114.4\n",
-      "1990-02-01,120.1\n",
-      "1990-03-01,119.6\n",
-      "1990-04-01,119.1\n",
-      "1990-05-01,115.8\n",
-      "1990-06-01,112.4\n",
-      "1990-07-01,113.1\n",
-      "1990-08-01,115.0\n",
-      "1990-09-01,121.4\n",
-      "1990-10-01,127.1\n",
-      "1990-11-01,129.9\n",
-      "1990-12-01,130.5\n",
-      "1991-01-01,131.3\n",
-      "1991-02-01,131.4\n",
-      "1991-03-01,130.5\n",
-      "1991-04-01,128.3\n",
-      "1991-05-01,126.0\n",
-      "1991-06-01,123.6\n",
-      "1991-07-01,123.1\n",
-      "1991-08-01,124.3\n",
-      "1991-09-01,123.9\n",
-      "1991-10-01,125.0\n",
-      "1991-11-01,123.6\n",
-      "1991-12-01,124.7\n",
-      "1992-01-01,123.6\n",
-      "1992-02-01,122.9\n",
-      "1992-03-01,122.1\n",
-      "1992-04-01,122.0\n",
-      "1992-05-01,123.4\n",
-      "1992-06-01,123.7\n",
-      "1992-07-01,121.2\n",
-      "1992-08-01,118.5\n",
-      "1992-09-01,119.2\n",
-      "1992-10-01,121.8\n",
-      "1992-11-01,121.3\n",
-      "1992-12-01,121.1\n",
-      "1993-01-01,122.3\n",
-      "1993-02-01,124.2\n",
-      "1993-03-01,125.5\n",
-      "1993-04-01,125.6\n",
-      "1993-05-01,125.0\n",
-      "1993-06-01,123.1\n",
-      "1993-07-01,121.6\n",
-      "1993-08-01,118.8\n",
-      "1993-09-01,118.9\n",
-      "1993-10-01,119.5\n",
-      "1993-11-01,128.7\n",
-      "1993-12-01,121.9\n",
-      "1994-01-01,123.6\n",
-      "1994-02-01,126.8\n",
-      "1994-03-01,129.1\n",
-      "1994-04-01,133.9\n",
-      "1994-05-01,136.8\n",
-      "1994-06-01,135.7\n",
-      "1994-07-01,136.9\n",
-      "1994-08-01,138.3\n",
-      "1994-09-01,138.2\n",
-      "1994-10-01,143.5\n",
-      "1994-11-01,147.8\n",
-      "1994-12-01,148.3\n",
-      "1995-01-01,155.8\n",
-      "1995-02-01,161.2\n",
-      "1995-03-01,165.3\n",
-      "1995-04-01,167.2\n",
-      "1995-05-01,166.6\n",
-      "1995-06-01,164.3\n",
-      "1995-07-01,157.3\n",
-      "1995-08-01,148.5\n",
-      "1995-09-01,147.1\n",
-      "1995-10-01,147.8\n",
-      "1995-11-01,152.4\n",
-      "1995-12-01,156.8\n",
-      "1996-01-01,161.8\n",
-      "1996-02-01,162.4\n",
-      "1996-03-01,165.8\n",
-      "1996-04-01,164.9\n",
-      "1996-05-01,162.3\n",
-      "1996-06-01,156.3\n",
-      "1996-07-01,151.5\n",
-      "1996-08-01,149.9\n",
-      "1996-09-01,150.5\n",
-      "1996-10-01,157.8\n",
-      "1996-11-01,159.8\n",
-      "1996-12-01,165.8\n",
-      "1997-01-01,167.6\n",
-      "1997-02-01,169.8\n",
-      "1997-03-01,170.5\n",
-      "1997-04-01,170.4\n",
-      "1997-05-01,168.3\n",
-      "1997-06-01,163.1\n",
-      "1997-07-01,158.0\n",
-      "1997-08-01,157.3\n",
-      "1997-09-01,156.1\n",
-      "1997-10-01,151.5\n",
-      "1997-11-01,148.8\n",
-      "1997-12-01,144.0\n",
-      "1998-01-01,142.1\n",
-      "1998-02-01,140.1\n",
-      "1998-03-01,139.9\n",
-      "1998-04-01,136.8\n",
-      "1998-05-01,139.0\n",
-      "1998-06-01,138.7\n",
-      "1998-07-01,136.4\n",
-      "1998-08-01,132.2\n",
-      "1998-09-01,127.9\n",
-      "1998-10-01,126.4\n",
-      "1998-11-01,123.1\n",
-      "1998-12-01,120.4\n",
-      "1999-01-01,119.6\n",
-      "1999-02-01,119.7\n",
-      "1999-03-01,121.0\n",
-      "1999-04-01,121.7\n",
-      "1999-05-01,118.9\n",
-      "1999-06-01,117.0\n",
-      "1999-07-01,113.5\n",
-      "1999-08-01,113.1\n",
-      "1999-09-01,115.0\n",
-      "1999-10-01,120.7\n",
-      "1999-11-01,120.5\n",
-      "1999-12-01,122.4\n",
-      "2000-01-01,126.3\n",
-      "2000-02-01,130.7\n",
-      "2000-03-01,133.7\n",
-      "2000-04-01,135.0\n",
-      "2000-05-01,134.7\n",
-      "2000-06-01,138.2\n",
-      "2000-07-01,147.2\n",
-      "2000-08-01,148.2\n",
-      "2000-09-01,152.5\n",
-      "2000-10-01,157.8\n",
-      "2000-11-01,161.6\n",
-      "2000-12-01,170.6\n",
-      "2001-01-01,209.1\n",
-      "2001-02-01,218.6\n",
-      "2001-03-01,216.8\n",
-      "2001-04-01,202.8\n",
-      "2001-05-01,187.0\n",
-      "2001-06-01,171.1\n",
-      "2001-07-01,159.6\n",
-      "2001-08-01,149.3\n",
-      "2001-09-01,144.9\n",
-      "2001-10-01,137.6\n",
-      "2001-11-01,132.9\n",
-      "2001-12-01,131.0\n",
-      "2002-01-01,130.3\n",
-      "2002-02-01,129.1\n",
-      "2002-03-01,127.2\n",
-      "2002-04-01,126.1\n",
-      "2002-05-01,128.0\n",
-      "2002-06-01,132.0\n",
-      "2002-07-01,131.5\n",
-      "2002-08-01,132.0\n",
-      "2002-09-01,130.6\n",
-      "2002-10-01,133.5\n",
-      "2002-11-01,137.9\n",
-      "2002-12-01,141.6\n",
-      "2003-01-01,150.9\n",
-      "2003-02-01,163.6\n",
-      "2003-03-01,183.0\n",
-      "2003-04-01,188.7\n",
-      "2003-05-01,184.1\n",
-      "2003-06-01,177.6\n",
-      "2003-07-01,173.8\n",
-      "2003-08-01,175.8\n",
-      "2003-09-01,178.4\n",
-      "2003-10-01,180.7\n",
-      "2003-11-01,182.0\n",
-      "2003-12-01,185.6\n",
-      "2004-01-01,192.6\n",
-      "2004-02-01,198.4\n",
-      "2004-03-01,199.3\n",
-      "2004-04-01,200.2\n",
-      "2004-05-01,194.6\n",
-      "2004-06-01,197.7\n",
-      "2004-07-01,200.2\n",
-      "2004-08-01,206.0\n",
-      "2004-09-01,206.3\n",
-      "2004-10-01,214.0\n",
-      "2004-11-01,217.5\n",
-      "2004-12-01,220.1\n",
-      "2005-01-01,220.2\n",
-      "2005-02-01,219.6\n",
-      "2005-03-01,218.8\n",
-      "2005-04-01,226.6\n",
-      "2005-05-01,230.4\n",
-      "2005-06-01,232.8\n",
-      "2005-07-01,228.4\n",
-      "2005-08-01,227.5\n",
-      "2005-09-01,236.0\n",
-      "2005-10-01,256.0\n",
-      "2005-11-01,266.9\n",
-      "2005-12-01,279.3\n",
-      "2006-01-01,284.7\n",
-      "2006-02-01,272.7\n",
-      "2006-03-01,264.6\n",
-      "2006-04-01,256.4\n",
-      "2006-05-01,251.4\n",
-      "2006-06-01,242.7\n",
-      "2006-07-01,231.9\n",
-      "2006-08-01,228.3\n",
-      "2006-09-01,225.2\n",
-      "2006-10-01,228.2\n",
-      "2006-11-01,228.5\n",
-      "2006-12-01,233.0\n",
-      "2007-01-01,244.5\n",
-      "2007-02-01,256.9\n",
-      "2007-03-01,272.1\n",
-      "2007-04-01,283.4\n",
-      "2007-05-01,281.9\n",
-      "2007-06-01,283.1\n",
-      "2007-07-01,282.0\n",
-      "2007-08-01,273.8\n",
-      "2007-09-01,272.6\n",
-      "2007-10-01,285.2\n",
-      "2007-11-01,291.5\n",
-      "2007-12-01,314.5\n",
-      "2008-01-01,338.6\n",
-      "2008-02-01,348.5\n",
-      "2008-03-01,368.5\n",
-      "2008-04-01,381.8\n",
-      "2008-05-01,410.6\n",
-      "2008-06-01,437.9\n",
-      "2008-07-01,473.8\n",
-      "2008-08-01,491.9\n",
-      "2008-09-01,508.2\n",
-      "2008-10-01,498.3\n",
-      "2008-11-01,454.2\n",
-      "2008-12-01,411.1\n",
-      "2009-01-01,359.0\n",
-      "2009-02-01,319.0\n",
-      "2009-03-01,293.5\n",
-      "2009-04-01,308.6\n",
-      "2009-05-01,292.7\n",
-      "2009-06-01,264.8\n",
-      "2009-07-01,250.0\n",
-      "2009-08-01,246.2\n",
-      "2009-09-01,235.0\n",
-      "2009-10-01,243.6\n",
-      "2009-11-01,246.8\n",
-      "2009-12-01,245.6\n",
-      "2010-01-01,255.8\n",
-      "2010-02-01,269.4\n",
-      "2010-03-01,274.8\n",
-      "2010-04-01,289.9\n",
-      "2010-05-01,290.6\n",
-      "2010-06-01,286.0\n",
-      "2010-07-01,271.9\n",
-      "2010-08-01,279.4\n",
-      "2010-09-01,291.3\n",
-      "2010-10-01,310.1\n",
-      "2010-11-01,314.0\n",
-      "2010-12-01,326.0\n",
-      "2011-01-01,341.2\n",
-      "2011-02-01,357.2\n",
-      "2011-03-01,373.7\n",
-      "2011-04-01,386.5\n",
-      "2011-05-01,395.7\n",
-      "2011-06-01,405.4\n",
-      "2011-07-01,413.4\n",
-      "2011-08-01,413.2\n",
-      "2011-09-01,419.0\n",
-      "2011-10-01,430.8\n",
-      "2011-11-01,441.1\n",
-      "2011-12-01,443.5\n",
-      "2012-01-01,430.6\n",
-      "2012-02-01,410.4\n",
-      "2012-03-01,405.8\n",
-      "2012-04-01,425.7\n",
-      "2012-05-01,451.5\n",
-      "2012-06-01,455.9\n",
-      "2012-07-01,451.3\n",
-      "2012-08-01,433.6\n",
-      "2012-09-01,432.6\n",
-      "2012-10-01,436.1\n",
-      "2012-11-01,433.9\n",
-      "2012-12-01,437.7\n",
-      "2013-01-01,442.6\n",
-      "2013-02-01,448.7\n",
-      "2013-03-01,444.3\n",
-      "2013-04-01,462.2\n",
-      "2013-05-01,470.4\n",
-      "2013-06-01,450.3\n",
-      "2013-07-01,428.3\n",
-      "2013-08-01,384.5\n",
-      "2013-09-01,375.0\n",
-      "2013-10-01,369.4\n",
-      "2013-11-01,369.2\n",
-      "2013-12-01,365.2\n",
-      "2014-01-01,364.9\n",
-      "2014-02-01,382.0\n",
-      "2014-03-01,389.6\n",
-      "2014-04-01,401.0\n",
-      "2014-05-01,420.0\n",
-      "2014-06-01,403.8\n",
-      "2014-07-01,389.9\n",
-      "2014-08-01,380.4\n",
-      "2014-09-01,376.4\n",
-      "2014-10-01,371.9\n",
-      "2014-11-01,373.3\n",
-      "2014-12-01,376.8\n",
-      "2015-01-01,379.9\n",
-      "2015-02-01,378.4\n",
-      "2015-03-01,371.2\n",
-      "2015-04-01,372.6\n",
-      "2015-05-01,376.4\n",
-      "2015-06-01,377.0\n",
-      "2015-07-01,363.2\n",
-      "2015-08-01,348.3\n",
-      "2015-09-01,360.0\n",
-      "2015-10-01,347.3\n",
-      "2015-11-01,344.3\n",
-      "2015-12-01,353.1\n",
-      "2016-01-01,338.0\n",
-      "2016-02-01,323.2\n",
-      "2016-03-01,314.3\n",
-      "2016-04-01,319.5\n",
-      "2016-05-01,320.6\n",
-      "2016-06-01,312.0\n",
-      "2016-07-01,290.1\n",
-      "2016-08-01,270.3\n",
-      "2016-09-01,263.7\n",
-      "2016-10-01,263.2\n",
-      "2016-11-01,265.5\n",
-      "2016-12-01,267.3\n",
-      "2017-01-01,270.6\n",
-      "2017-02-01,288.0\n",
-      "2017-03-01,297.3\n",
-      "2017-04-01,304.5\n",
-      "2017-05-01,299.8\n",
-      "2017-06-01,296.7\n",
-      "2017-07-01,282.4\n",
-      "2017-08-01,263.8\n",
-      "2017-09-01,258.6\n",
-      "2017-10-01,264.3\n",
-      "2017-11-01,278.7\n",
-      "2017-12-01,290.9\n",
-      "2018-01-01,292.1\n",
-      "2018-02-01,307.7\n",
-      "2018-03-01,307.5\n",
-      "2018-04-01,307.8\n",
-      "2018-05-01,305.3\n",
-      "2018-06-01,301.4\n",
-      "2018-07-01,293.9\n",
-      "2018-08-01,295.1\n",
-      "2018-09-01,298.4\n",
-      "2018-10-01,310.1\n",
-      "2018-11-01,318.6\n",
-      "2018-12-01,321.9\n",
-      "2019-01-01,321.9\n",
-      "2019-02-01,332.5\n",
-      "2019-03-01,329.2\n",
-      "2019-04-01,326.5\n",
-      "2019-05-01,325.6\n",
-      "2019-06-01,318.2\n",
-      "2019-07-01,312.2\n",
-      "2019-08-01,300.4\n",
-      "2019-09-01,297.3\n",
-      "2019-10-01,299.0\n",
-      "2019-11-01,294.5\n",
-      "2019-12-01,277.4\n",
-      "2020-01-01,280.8\n",
-      "2020-02-01,279.9\n",
-      "2020-03-01,282.5\n",
-      "2020-04-01,294.8\n",
-      "2020-05-01,294.2\n",
-      "2020-06-01,285.3\n",
-      "2020-07-01,280.9\n",
-      "2020-08-01,277.9\n",
-      "2020-09-01,280.7\n",
-      "2020-10-01,286.6\n",
-      "2020-11-01,286.0\n",
-      "2020-12-01,292.1\n",
-      "2021-01-01,307.5\n",
-      "2021-02-01,325.3\n",
-      "2021-03-01,333.8\n",
-      "2021-04-01,352.7\n",
-      "2021-05-01,366.5\n",
-      "2021-06-01,407.4\n",
-      "2021-07-01,419.080\n",
-      "2021-08-01,411.683\n",
-      "2021-09-01,421.322\n",
-      "2021-10-01,483.638\n",
-      "2021-11-01,539.354\n",
-      "2021-12-01,615.654\n",
-      "2022-01-01,643.475\n",
-      "2022-02-01,677.806\n",
-      "2022-03-01,674.724\n",
-      "\n"
-     ]
-    }
-   ],
    "source": [
-    "import requests\n",
-    "\n",
-    "url = 'https://app-learninglab.inria.fr/moocrr/gitlab/1d334d5105a1a432e18f2e361780bab5/mooc-rr/raw/master/module2/exo4/PCU325311325311.csv?inline=false'\n",
-    "data = requests.get(url).text\n",
-    "print(data)"
+    "This data gives the long-term evolution of nitrogen fertilizer price in USD"
    ]
   },
   {
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "We convert this big string into csv"
+    "First we import data from our gitlab repo."
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
+   "execution_count": 1,
    "metadata": {},
    "outputs": [],
    "source": [
     "import io\n",
     "import pandas as pd\n",
-    "df = pd.read_csv(io.StringIO(data), sep=',', decimal='.')\n",
+    "df = pd.read_csv('https://app-learninglab.inria.fr/moocrr/gitlab/1d334d5105a1a432e18f2e361780bab5/mooc-rr/raw/master/module2/exo4/PCU325311325311.csv?inline=false', sep=',', decimal='.')\n",
     "df.columns = ['date', 'price']"
    ]
   },
@@ -627,7 +56,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [
     {
@@ -636,7 +65,7 @@
        "'1975-12-01'"
       ]
      },
-     "execution_count": 3,
+     "execution_count": 2,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -647,7 +76,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 4,
+   "execution_count": 3,
    "metadata": {},
    "outputs": [
     {
@@ -656,7 +85,7 @@
        "Timestamp('1975-01-01 00:12:00')"
       ]
      },
-     "execution_count": 4,
+     "execution_count": 3,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -668,7 +97,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 4,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -686,16 +115,16 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 5,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "[<matplotlib.lines.Line2D at 0x7efdd16b4400>]"
+       "[<matplotlib.lines.Line2D at 0x7f8391afabe0>]"
       ]
      },
-     "execution_count": 6,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     },
@@ -728,7 +157,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": 6,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -738,7 +167,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 8,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -748,7 +177,7 @@
        "dtype: float64"
       ]
      },
-     "execution_count": 8,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -766,7 +195,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 9,
+   "execution_count": 8,
    "metadata": {},
    "outputs": [
     {
@@ -776,7 +205,7 @@
        "dtype: float64"
       ]
      },
-     "execution_count": 9,
+     "execution_count": 8,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -794,7 +223,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 10,
+   "execution_count": 9,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -803,7 +232,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 11,
+   "execution_count": 10,
    "metadata": {},
    "outputs": [
     {
@@ -813,7 +242,7 @@
        "dtype: float64"
       ]
      },
-     "execution_count": 11,
+     "execution_count": 10,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -831,7 +260,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 12,
+   "execution_count": 11,
    "metadata": {},
    "outputs": [
     {
@@ -841,7 +270,7 @@
        "dtype: float64"
       ]
      },
-     "execution_count": 12,
+     "execution_count": 11,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -850,6 +279,20 @@
     "np.around(prices_after_2000.std(ddof=1), decimals=2)"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Conclusion of the study"
+   ]
+  },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "We shown that after year 2000, the average price and variance of nitrogen fertilizer greatly increased compared to before year 2000."
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": null,
-- 
2.18.1