我使用SAP输出的数据进行工作,但它既不是CSV格式(因为它不会引用包含其分隔符的字符串),也不是固定宽度格式(因为它具有多字节字符)。它可以说是一种“逐个字符”的“固定宽度”格式。
目前,为了将其读入pandas,我会先读取文件,获取分隔符位置,围绕分隔符切割每一行,然后将其保存到一个适当的CSV文件中,这样我就可以轻松地读取它。
我发现pandas read_csv可以获取文件缓冲区。我该如何直接将我的流传递给它,而不保存CSV文件?我应该生成器吗?我能否在没有给出文件句柄的情况下获得csv.writer.writerow输出?
以下是我的代码:
import pandas as pd
caminho= r'C:\Users\user\Documents\SAP\Tests\\'
arquivo = "ExpComp_01.txt"
tipo_dado = {"KEY_GUID":"object", "DEL_IND":"object", "HDR_GUID":"object", , "PRICE":"object", "LEADTIME":"int16", "MANUFACTURER":"object", "LOAD_TIME":"object", "APPR_TIME":"object", "SEND_TIME":"object", "DESCRIPTION":"object"}
def desmembra(linha, limites):
# This functions receives each delimiter's index and cuts around it
posicao=limites[0]
for limite in limites[1:]:
yield linha[posicao+1:limite]
posicao=limite
def pre_processa(arquivo):
import csv
import os
# Translates SAP output in standard CSV
with open(arquivo,"r", encoding="mbcs") as entrada, open(arquivo[:-3] +
"csv", "w", newline="", encoding="mbcs") as saida:
escreve=csv.writer(saida,csv.QUOTE_MINIMAL, delimiter=";").writerow
for line in entrada:
# Find heading
if line[0]=="|":
delimitadores = [x for x, v in enumerate(line) if v == '|']
if line[-2] != "|":
delimitadores.append(None)
cabecalho_teste=line[:50]
escreve([campo.strip() for campo in desmembra(line,delimitadores)])
break
for line in entrada:
if line[0]=="|" and line[:50]!=cabecalho_teste:
escreve([campo.strip() for campo in desmembra(line, delimitadores)])
pre_processa(caminho+arquivo)
dados = pd.read_csv(caminho + arquivo[:-3] + "csv", sep=";",
header=0, encoding="mbcs", dtype=tipo_dado)
此外,如果您能分享最佳实践: 我有一些奇怪的日期时间字符串,如
20.120.813.132.432
,我可以成功地使用以下方法进行转换:dados["SEND_TIME"]=pd.to_datetime(dados["SEND_TIME"], format="%Y%m%d%H%M%S")
dados["SEND_TIME"].replace(regex=False,inplace=True,to_replace=r'.',value=r'')
我无法为此编写解析器,因为我的日期存储在不同的字符串格式中。在导入期间指定转换器是否会更快,还是在最后由pandas逐列执行转换?我有一个类似的问题,需要将代码
99999999
添加点99.999.999
。我不知道是否应该编写转换器或等到导入后执行df.replace
。
编辑 - 示例数据:| KEY_GUID|DEL_IND| HDR_GUID|Prod_CD |DESCRIPTION | PRICE|LEADTIME|MANUFACTURER| LOAD_TIME|APPR_TIME | SEND_TIME|
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|000427507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123636|Vneráéíoaeot.sadot.m | 29,55 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.157 |
|000527507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123643|Tnerasodaeot|sadot.m | 122,91 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.141 |
|0005DB50112F9E69E10000000A1D2028| |384BB350BF56315DE20062700D627978|75123676|Dnerasodáeot.sadot.m |252.446,99 |3 |POLAND |20.121.226.175.640 |20121226183608|20.121.222.000.015 |
|000627507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123652|Pner|sodaeot.sadot.m | 657,49 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.128 |
|000727507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83| |Rnerasodaeot.sadot.m | 523,63 |30 | |20.120.813.132.432 |20120813132929|20.120.707.010.119 |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| KEY_GUID|DEL_IND| HDR_GUID|Prod_CD |DESCRIPTION | PRICE|LEADTIME|MANUFACTURER| LOAD_TIME|APPR_TIME | SEND_TIME|
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |000827507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123603|Inerasodéeot.sadot.m | 2.073,63 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.127 |
|000927507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123662|Ane|asodaeot.sadot.m | 0,22 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.135 |
|000A27507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123626|Pneraíodaeot.sadot.m | 300,75 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.140 |
|000B27507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83| |Aneraéodaeot.sadot.m | 1,19 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.131 |
|000C27507E64FB29E2006281548EB186| |4C1AD7E25DC50D61E10000000A19FF83|75123613|Cnerasodaeot.sadot.m | 30,90 |30 | |20.120.813.132.432 |20120813132929|20.120.505.010.144 |
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
我需要处理其他表格,这些表格包含其他字段,都是这种一般的形式。我只能相信标题中的分隔符。此外,数据中可能会有重复的标题。它看起来像一个矩阵式的打印输出。
read_fwf
函数,但它没有像read_csv
那样多的调整选项。 - EdChumread_fwf
不够快。由于每个周期需要处理数百万条记录,因此我没有尝试。我在处理含有多字节字符的固定宽度时遇到了很多麻烦。我的第一次尝试是使用struct.unpack
。这种预处理实际上很快,但我希望避免保存新的桥接文件。 - mvbentes