要执行您所寻找的操作-在x轴上的特定位置设置每个条形图，您需要为每个条形图使用set_x()。您可以使用container.get_children()获取此值，然后移动它。
请注意，我将数据作为dataframe，并添加了一个名为pos的列。这将定义每个条与x轴零的距离。绘制条形图，然后使用set_x（）移动条形图，使用plt.xlim()和plt.xticks()对齐刻度和标签。希望这就是你要找的...

# creating the dataset - Using dataframe and adding pos column for distance from zero
data = {'courses' : ['C', 'C++', 'Java', 'Python'], 'values' : [20, 15, 30, 35], 'pos' : [2, 3, 5, 7]}
df=pd.DataFrame(data)

fig = plt.figure(figsize = (10, 5))
# creating the bar plot
plt.bar(df['courses'], df['values'], color ='maroon', width = 0.4)
plt.xlabel("Courses offered")
plt.ylabel("No. of students enrolled")
plt.title("Students enrolled in different courses")

## Set xlim from 0 to largest value plus 0.5 to show all bars
plt.xlim(0, df.pos.max()+0.5)

## Access each bar and set the position based on value in df.pos
for container in plt.gca().containers:
        for i, child in enumerate(container.get_children()):
            child.set_x(df.pos[i]-0.2) ## 0.2 as you set width=0.4

##Adjust ticks and ticklabels
plt.xticks(ticks=df.pos, labels=df.courses)
plt.show()

也许你只需要重新排列一下字典的键就行了？

d = {k: data[k] for k in ["Java", "C++", "Python", "C"]} # <-- re-ordered `data`
P = [3, 5, 8, 13] # <-- positions of each bar/x-tick
W = 1.5 # <-- width of the bars

plt.figure(figsize=(7, 4))

plt.bar(P, d.values(), color="maroon", width=W)

plt.xticks(P, d.keys())
plt.xlim(0, max(P) + W)

输出：