如何使Matplotlib在X轴上显示日期而不在周末绘制空间

Question

I've been using this example: and I am trying to use the code shown below to make grid locate the first date (first date in csv file, so it might be eg 3. July instead of 1. July).

months = matplotlib.dates.MonthLocator()
ax.xaxis.set_major_locator(months)

However when I write the code above all dates disappear, and the grid show no lines marking the x-axis (see code 2 below):

How can I make set_major_locator() to locate the first day in month (first available from csv file)? In the picture below I've made the grid locate first day in month by using

ax.plot(r.date, r.adj_close, 'o-')
months = matplotlib.dates.MonthLocator()
ax.xaxis.set_major_locator(months)

The problem here is that empty days make spaces, and this makes problems when I'm trying to plot lines on the graph.

edit: Code 1 (puts grid in right place, but makes trouble when I try to plot lines as it makes spaces in weekends etc):

def plot1(price, date):
    # first we'll do it the default way, with gaps on weekends
    fig, ax = plt.subplots()
    ax.plot(date, price, 'o-',c='black', markersize=2.7, linewidth=0.9)
    ax.xaxis.set_major_formatter(mdates.DateFormatter('%m-%Y-%d'))
    days_locator = mdates.DayLocator(bymonthday=[1,])
    ax.xaxis.set_major_locator(days_locator)
    ax.set_title("Default")
    fig.autofmt_xdate()
    ax.grid()
    plt.show()

Code 2 (set_major_locator() doesn't work):

def plot2(price, date):
    # next we'll write a custom formatter
    N = len(price)
    ind = np.arange(N)  # the evenly spaced plot indices
    def format_date(x, pos=None):
        thisind = np.clip(int(x + 0.5), 0, N - 1)
        return date[thisind].strftime('%Y-%m-%d')
    fig, ax = plt.subplots()
    ax.plot(ind, price, 'o-',c='black', markersize=2.7, linewidth=0.9)
    ax.xaxis.set_major_formatter(mticker.FuncFormatter(format_date))
    ax.set_title("Custom tick formatter")
    days_locator = mdates.DayLocator(bymonthday=[1,])
    ax.xaxis.set_major_locator(days_locator)
    fig.autofmt_xdate()
    ax.grid()
    plt.show()

Answer 1

To locate the first day of months, you should use:

days_locator = mdates.DayLocator(bymonthday=[1,])
ax.xaxis.set_major_locator(days_locator)