I have a dataframe, df, containing information about a company, the country they are located in, and the year they were founded. I now need to plot the development of the amount of companies founded per country for each year in the dataset (between 1995 - 2015) in a line, however all I manage to create is a pie chart with the total companies funded per country, but not including the year_founded information.

The data looks like this:

Ideally I would like to plot the total amount of companies per country in a line chart with different lines per country.

Any ideas on how to approach this problem?

CodePudding user response：

IIUC, you can use crosstab and plot.line:

ax = pd.crosstab(df['Year_founded'], df['Country']).plot.line()
ax.set_ylabel('Number of founded companies')
from matplotlib.ticker import MaxNLocator
ax.xaxis.set_major_locator(MaxNLocator(integer=True))

output:

crosstab:

Country       CAN  NLD  USA
Year_founded               
1996            0    0    1
1999            0    1    0
2000            1    0    1
2004            0    1    0
2014            1    0    0

CodePudding user response：

You could use groupby and reindex so that all years from 1995-2015 are in your graph:

data = df.groupby(["Country", "Year_founded"])["Company"].count().unstack(0).reindex(range(1995,2016)).fillna(0)

>>> data.plot()

>>> data
Country       CAN  NLD  USA
Year_founded               
1995          0.0  0.0  0.0
1996          0.0  0.0  1.0
1997          0.0  0.0  0.0
1998          0.0  0.0  0.0
1999          0.0  1.0  0.0
2000          1.0  0.0  1.0
2001          0.0  0.0  0.0
2002          0.0  0.0  0.0
2003          0.0  0.0  0.0
2004          0.0  1.0  0.0
2005          0.0  0.0  0.0
2006          0.0  0.0  0.0
2007          0.0  0.0  0.0
2008          0.0  0.0  0.0
2009          0.0  0.0  0.0
2010          0.0  0.0  0.0
2011          0.0  0.0  0.0
2012          0.0  0.0  0.0
2013          0.0  0.0  0.0
2014          1.0  0.0  0.0
2015          0.0  0.0  0.0