Question

我正在努力解决使用pandas regex通过str.extract来使"name"列中的每一行生成列"description"的函数的一些问题。我使用的是regex而不是split，因为代码必须能够管理各种格式。

必须修改该功能以确认各种条件。

数据帧：

import pandas as pd
import re

df = pd.DataFrame(["LONG AXP UN X3 VON", "SHORT BIDU UN 5x VON", "SHORT GOOG VON", "LONG GOOG VON"], columns=["name"])

输入：

name
"LONG AXP UN X3 VON"
"SHORT BIDU UN 5x VON"
"SHORT GOOG VON"
"LONG GOOG VON"

当前代码：

description_map = {"AXP":"American Express", "BIDU":"Baidu"}
sign_map = {"LONG": "", "SHORT": "-"}
def f(strseries):
    stock = strseries.str.extract(r"\s(\S+)\s").map(description_map)
    leverage = strseries.str.extract(r"(X\d+|\d+X)\s", flags=re.IGNORECASE)
    sign = strseries.str.extract(r"(\S+)\s").map(sign_map)
    return "Tracks " + stock + " with " + sign + leverage + " leverage"

df["description"] = f(df["name"])

当前输出：

name                        description
"LONG AXP UN X3 VON"        "Tracks American Express with X3 leverage"
"SHORT BIDU UN 5x VON"      "Tracks Baidu with -5x leverage"
"SHORT GOOG VON"            ""
"LONG GOOG VON"             ""

期望的输出：

name                        description
"LONG AXP UN X3 VON"        "Tracks American Express with 3x leverage"
"SHORT BIDU UN 5x VON"      "Tracks Baidu inversely with -5x leverage"
"SHORT GOOG VON"            "Tracks inversely"
"LONG GOOG VON"             "Tracks"

意义：

如果sign是"-"，我怎样才能将direction = "inversely"添加到字符串中？
如果stock中没有name与字典description_map匹配：设置stock = ""并返回字符串。
如果在leverage中找不到name：忽略部分"with" + sign + leverage + " leverage"。
拆分并重新排序sign + leverage，以便始终按-5x"的顺序显示，无论是否输入"SHORT X5"。

Answer 1

我花了一些时间写这个函数：

description_map = {"AXP":"American Express", "BIDU":"Baidu"}
sign_map = {"LONG": "", "SHORT": "-"}

stock_match = re.compile(r"\s(\S+)\s")
leverage_match = re.compile("[0-9]x|x[0-9]|X[0-9]|[0-9]X")

def f(value):

    f1 = lambda x: description_map[stock_match.findall(x)[0]] if stock_match.findall(x)[0] in description_map else ''
    f2 = lambda x: leverage_match.findall(x)[0] if len(leverage_match.findall(x)) > 0 else ''
    f3 = lambda x: '-' if 'SHORT' in x else ''

    stock = f1(value)
    leverage = f2(value)
    sign = f3(value)

    statement = "Tracks " + stock

    if stock == "":
        if sign == '-':
            return statement + "{}".format('inversely')
        else:
            return "Tracks"

    if leverage[0].replace('X','x') == 'x':
        leverage = leverage[1]+leverage[0].replace('X','x')

    if leverage != '' and sign == '-':
        statement += " {} with {}{} leverage".format('inversely', sign, leverage)
    elif leverage != '' and sign == '':
        statement += " with {} leverage".format(leverage)
    else:
        if sign == '-':
            statement += " {} ".format('Inversely')

    return statement

df["description"] = df["name"].map(lambda x:f(x))

输出：

In [97]: %paste
import pandas as pd
import re

df = pd.DataFrame(["LONG AXP UN X3 VON", "SHORT BIDU UN 5x VON", "SHORT GOOG VON", "LONG GOOG VON"], columns=["name"])

## -- End pasted text --

In [98]: df
Out[98]: 
                   name
0    LONG AXP UN X3 VON
1  SHORT BIDU UN 5x VON
2        SHORT GOOG VON
3         LONG GOOG VON

In [99]: df["description"] = df["name"].map(lambda x:f(x))

In [100]: df
Out[100]: 
                   name                               description
0    LONG AXP UN X3 VON  Tracks American Express with 3x leverage
1  SHORT BIDU UN 5x VON  Tracks Baidu inversely with -5x leverage
2        SHORT GOOG VON                          Tracks inversely
3         LONG GOOG VON                                    Tracks

熊猫：有条件地从列内容生成描述

1 个答案: