如何解决如何将列表中的多个项目与另一个列表中的一个元素匹配?
我需要将列表 array
(364 项)中的项与列表 months
(12 项)进行匹配。 array
中将有多个项目对应于 months
中的每个月。
array = ['309','307','303','296','322','340','321','314','327','315','316','333','286','289','290','317','348','398','396','404','424','402','357','320','328','312','293','302','281',' 0','326','332','242','259','268','280','308','298','300','284','337','288','373','301','272','318','297','299','306','325','334','390','339','343','336','366','383','379','355','342','369','362','359','360','380','388','393','347','335','313','309','304','354','364','329','346','338','285','310','311','323','351','345','372','367','356','331','305','319','324','352','287','292','291','294','282','279','344','275','270','283','295','276','263','266','256','257','269','258','273','277','274','267','255','239','278','246','252','265','291']
months=['January 2020','February 2020','March 2020','April 2020','May 2020','June 2020','July 2020','August 2020','September 2020','October 2020','November 2020','December 2020']
array
中的 364 个值对应于 2020 年最后一年的每一天的臭氧数据,因此我需要将每 31 个(或 30,在 2 月和 12 月的情况下甚至是 29 个)项目与正确的月份,考虑到 'array' 中的第一个值对应于日期 01-01-2020,最后一个值对应于 29-12-2020。我真的不知道是否有命令,或者我是否必须直接用代码来做。
我编写代码的最终目标是使用 matplotlib 之类的任何库绘制 x 轴上的 months
和 y 轴上的 array
:
import matplotlib.pyplot as plt
plt.plot(months,array)
plt.ylabel('Ozone Madrid')
plt.xlabel('Months')
plt.show()
目前我无法绘制此图,因为采用 plt.plot()
的参数(两个列表)没有相同数量的项目。这就是我想到上一步的原因。
有没有其他方法可以更快更有效地做到这一点?
解决方法
您可以根据它在一年中的位置找到一天的月份:
from datetime import date
def get_month_from_yday(year,yday):
'''
year is the reference year
yday is the day's position in the year (0 is January 1st etc.)
'''
return date.fromordinal(date(year,1,1).toordinal() + yday).strftime("%B %Y")
输入
# Month if the 1st day of the year
print(get_month_from_yday(2020,0))
# Month if the 32nd day of the year
print(get_month_from_yday(2020,31))
# Month if the 361st day of the year
print(get_month_from_yday(2020,360))
输出
January 2020
February 2020
December 2020
使用此函数,您可以根据数组的索引获取当天的月份。
显示图表
为了区分图表上的每个月,我为每个月绘制了不同颜色的矩形。 我还在每个月的月初在 x 轴上显示了一个勾号。
from datetime import date
import matplotlib.pyplot as plt
fig,ax = plt.subplots()
def get_month_from_yday(year,1).toordinal() + yday).strftime("%B %Y")
# Input value
array = ['309','307','303','296','322','340','321','314','327','315','316','333','286','289','290','317','348','398','396','404','424','402','357','320','328','312','293','302','281',' 0','326','332','242','259','268','280','308','298','300','284','337','288','373','301','272','318','297','299','306','325','334','390','339','343','336','366','383','379','355','342','369','362','359','360','380','388','393','347','335','313','309','304','354','364','329','346','338','285','310','311','323','351','345','372','367','356','331','305','319','324','352','287','292','291','294','282','279','344','275','270','283','295','276','263','266','256','257','269','258','273','277','274','267','255','239','278','246','252','265','291']
months=['January 2020','February 2020','March 2020','April 2020','May 2020','June 2020','July 2020','August 2020','September 2020','October 2020','November 2020','December 2020']
# List of months for each of the array values
data_month = [get_month_from_yday(2020,i) for i in range(len(array))]
# List of array values as integer
y_values = [int(x) for x in array]
# List containing the index of the months starts
month_starts_index = [i for i in range(len(data_month)) if i==0 or (i!=0 and data_month[i-1] != data_month[i]) or i == len(data_month)-1]
# Draw a vertical span of different color for each month
colors=['red','blue']
for i in range(len(month_starts_index)):
if i!=0:
ax.axvspan(month_starts_index[i-1],month_starts_index[i],color=colors[i%len(colors)],alpha=0.3)
# Display a tick on the x-axis at each month start
plt.xticks(month_starts_index,[month for i,month in enumerate(data_month) if i in month_starts_index],rotation=45)
plt.xlabel('Months')
plt.ylabel('Ozone Madrid')
plt.xlim(0,len(y_values)-1)
plt.plot(range(len(y_values)),y_values)
plt.show()
,
您可以使用 monthrange
(内置)中的 calendar
函数来获取一个月的天数。你的代码应该是这样的
from calendar import monthrange
month_vals = []
for i in range(1,13):
vals = array[:monthrange(2020,i)[1]]
array = array[monthrange(2020,i)[1]:]
month_vals.append(vals)
注意:您的 array
有 366 个值,而不是 364 个
好的,所以西班牙 Stack Overflow 上的另一个人(所有功劳都归于用户:Rubiales Alberto)给了我钥匙,所以如果对其他人有帮助,我就把它贴在这里。>
尽管我仍然需要在 months
和 array in order to plot it,we can create the months list by using
pandas` 库中拥有相同数量的参数。代码如下:
输入
import pandas as pd
import matplotlib.pyplot as plt
array = ['309','291']
#The numbers of the list are string type,so we transform them into integers:
array = [int(n) for n in array]
#We create a list of months,this is the important command-line:
months = pd.date_range("01-01-2020","31-12-2020")
plt.plot(months,array)
plt.ylabel('Ozone Madrid')
plt.xlabel('Months')
plt.show()
输出
# (It doesn't allow me to upload images yet cause I'm a beginner here,# but it gives me the linear graph that I needed)
无论如何,我不太确定为什么使用 pd.date_range("date1","date2")
库中的 pandas
进行绘图,将数据自动调整为这种图表,而不是人们在此处发布的其他选项,但是由于pandas
被编码用于数据分析,接下来我要做的是阅读其文档。
非常感谢您的帮助
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