使用gviz_api.py的日期格式

Question

我正在使用gviz_api(google-visualization-python)来构建一些折线图. http://code.google.com/p/google-visualization-python/

我编辑了一个从谷歌文档中获取的折线图示例.
但是,我不确定如何将日期传递给DataTable

这是我一直在使用的编辑过的例子. https://gist.github.com/3941946

这是我有一个问题的代码

 # Creating the data
 description = {"year": ("string", "Year"),
             "sales": ("number", "Sales"),
             "expenses": ("number", "Expenses")}

 data = [{"year": '2004', "sales": 1000, "expenses": 300}, 
      {"year": '2005', "sales": 1200, "expenses": 400}, 
      {"year": '2006', "sales": 1300, "expenses": 500}, 
      {"year": '2007', "sales": 1400, "expenses": 600}, 
      {"year": '2008', "sales": 1500, "expenses": 800}]
  # Loading it into gviz_api.DataTable
  data_table = gviz_api.DataTable(description)
  data_table.LoadData(data)

如何使用gviz_api将日期加载到DataTable中？

谷歌文档描述了如何使用javascript创建一个新的Date(),但是,我想继续使用gviz_api.py.

来自https://developers.google.com/chart/interactive/docs/dev/implementing_data_source#jsondatatable 的Google文档中的说明

*JSON修改Google的帮助程序库以及发送给Google的所有查询都返回了略微非标准版本的JSON/JSONP.如果您没有自己解析返回的代码,这对您来说无关紧要.Visualization API客户端支持JSON的标准版本和修改版本.以下是差异的摘要:

JSON不支持JavaScript Date值(例如,"new Date(2008,1,28,0,31,26)"; API实现.但是,API现在支持日期的自定义有效JSON表示形式字符串格式如下:日期(年,月,日[,小时,分钟,秒[,毫秒]]),其中一天中的所有内容都是可选的,而月份是从零开始的.

JSON对字典键使用双引号; API实现使用不带引号的密钥.

JSON需要围绕字符串值使用双引号; API实现使用单引号.*

Answer 1

您可以像在标准Python中一样处理创建日期 - API为您处理转换为JS.所有你需要做的就是import datetime在你的脚本的开始,为改变列类型year从string到date,然后创建的日期,你会在标准Python:

# This is the first modification - importing the library
import datetime
import gviz_api

# page_template stays the same
# ...

def main():
  # Creating the data
  # Here we change the type of column "year" to "date"
  description = {"year": ("date", "Year"),
                 "sales": ("number", "Sales"),
                 "expenses": ("number", "Expenses")}

  # Here we switch out the string dates with an actual Python datetime.date
  # The conversion happens in the the subsequent functions, giving you a 
  # date that is usable in the JS
  data = [{"year": datetime.date(2007,3,7), "sales": 1000, "expenses": 300},
          {"year": datetime.date(2009,6,11), "sales": 1200, "expenses": 400},
          {"year": datetime.date(2009,3,1), "sales": 1300, "expenses": 500},
          {"year": datetime.date(2010,8,6), "sales": 1401, "expenses": 600},
          {"year": datetime.date(2011,7,13), "sales": 1500, "expenses": 800}]
  # Loading it into gviz_api.DataTable
  data_table = gviz_api.DataTable(description)
  data_table.LoadData(data)

  # Creating a JavaScript code string
  jscode = data_table.ToJSCode("jscode_data",
                               columns_order=("year", "sales", "expenses"),
                               order_by="year")
  # Creating a JSon string
  json = data_table.ToJSon(columns_order=("year", "sales", "expenses"),
                           order_by="year")

  # Putting the JS code and JSon string into the template
  print "Content-type: text/html"
  print
  print page_template % vars()


if __name__ == '__main__':
  main()