Matplotlib doesn’t plot the lines on the chart

Question

I need to plot this dataframe called vars:

    data       var_brl  var_ars var_bob var_clp var_cop var_mxn var_pen var_pyg var_uyu
0   01/01/2020  0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00    0.00
1   02/01/2020  0.17    -0.10   0.14    -0.36   -1.01   -0.49   -0.41   0.41    0.16
2   03/01/2020  1.19    -0.22   0.07    1.65    -1.01   -0.04   0.11    0.49    -0.38
3   04/01/2020  1.19    -0.22   0.07    1.65    -1.01   -0.04   0.11    0.49    -0.38
4   05/01/2020  1.19    -0.22   0.07    1.65    -1.01   -0.04   0.11    0.49    -0.38
... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ...
135 15/05/2020  45.71   13.03   -0.07   10.07   18.98   26.43   3.78    1.81    18.19
136 16/05/2020  45.71   13.03   -0.07   10.07   18.98   26.43   3.78    1.81    18.19
137 17/05/2020  45.71   13.03   -0.07   10.07   18.98   26.43   3.78    1.81    18.19
138 18/05/2020  42.32   13.28   0.00    8.92    17.20   25.49   3.47    2.09    18.06
139 19/05/2020  43.20   13.43   0.00    8.88    16.69   25.08   3.46    2.10    18.06

What I need is a chart with several line plots, one for each column (except the date column that would be the x axis).

This the code I'm using:

labels = ['Real', 'Peso Argentino', 'Boliviano', 'Peso Chileno', 'Peso Colombiano', 'Peso Mexicano',
              'Novo Sol (Peru)', 'Guarani (Paraguai)', 'Peso Uruguaio']

fig, ax = plt.subplots(figsize=(16, 8))

months = mdates.MonthLocator()
months_fmt = mdates.DateFormatter('%m/%Y')
ax.xaxis.set_major_locator(months)
ax.xaxis.set_major_formatter(months_fmt)

lim_i = dt.datetime.strptime(vars.iloc[0, 0], '%d/%m/%Y')
lim_f = dt.datetime.strptime(vars.iloc[-1, 0], '%d/%m/%Y')

ax.set_xlim(lim_i, lim_f + dt.timedelta(days=30))

xlim = ax.get_xlim()[1]

for i in range(1, vars.shape[1]):
    if i == 1:
        c = 'red'
    else:
        c = 'grey'

    ax.plot(vars['data'], vars.iloc[:, i], color=c)
    ax.text(x=float(xlim) - 28, y=vars.iloc[-1, i], s=f'{labels[i-1]} ({vars.iloc[-1, i]}%)', alpha=0.4)

ax.tick_params(bottom=False, top=False, right=False, left=False)
ax.set_ylabel('Oscilação acumulada %')
plt.grid(False)

for key, spine in ax.spines.items():
    spine.set_visible(False)

plt.tight_layout()
plt.show()

And this is what I’m getting:

Everything works fine but the lines are not plotted. Can anyone see what I’m doing wrong?

Answer 1

Convert data to datetime

• ax.plot(vars['data'], vars.iloc[:, i], color=c)
  • vars['data'] is still a string, you never converted it to datetime
  • The tick locations are datetime and don't match the strings.
• It should be ax.plot(pd.to_datetime(df['data']), df.iloc[:, i], color=c), then your plot will work.