How can I change the x axis in matplotlib so there

问题:

So currently learning how to import data and work with it in matplotlib and I am having trouble even tho I have the exact code from the book.

This is what the plot looks like, but my question is how can I get it where there is no white space between the start and the end of the x-axis.

Here is the code:

import csv

from matplotlib import pyplot as plt
from datetime import datetime

# Get dates and high temperatures from file.
filename = \'sitka_weather_07-2014.csv\'
with open(filename) as f:
    reader = csv.reader(f)
    header_row = next(reader)

    #for index, column_header in enumerate(header_row):
        #print(index, column_header)
    dates, highs = [], []
    for row in reader:
        current_date = datetime.strptime(row[0], \"%Y-%m-%d\")
        dates.append(current_date)

        high = int(row[1])
        highs.append(high)

# Plot data. 
fig = plt.figure(dpi=128, figsize=(10,6))
plt.plot(dates, highs, c=\'red\')


# Format plot.
plt.title(\"Daily high temperatures, July 2014\", fontsize=24)
plt.xlabel(\'\', fontsize=16)
fig.autofmt_xdate()
plt.ylabel(\"Temperature (F)\", fontsize=16)
plt.tick_params(axis=\'both\', which=\'major\', labelsize=16)

plt.show()

回答1:

In matplotlib 2.x there is an automatic margin set at the edges, which ensures the data to be nicely fitting within the axis spines. In this case such a margin is probably desired on the y axis. By default it is set to 0.05 in units of axis span. To set the margin to 0 on the x axis, use

plt.margins(x=0)

or

ax.margins(x=0)

depending on the context. Also see the documentation.

In case you want to get rid of the margin in the whole script, you can use

plt.rcParams[\'axes.xmargin\'] = 0

at the beginning of your script (same for y of course). If you want to get rid of the margin entirely and forever, you might want to change the according line in the matplotlib rc file.

---

Alternatively to changing the margins, use plt.xlim(..) or ax.set_xlim(..) to manually set the limits of the axes such that there is no white space left.