converters and usecols usage in numpy

Open Excel data with Python. When reading, you need to convert "student number" and "ID" into characters for subsequent operations

df = pd.read_excel(path, converters={
    
    '学号': str, 'ID': str})

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The following is my experience to experience:

When I read data into python from Excel, I found that it was reading null values:

import pandas as pd 
df=pd.read_excel("D:/Python/05DataMineML/2022STU(1).xlsx")
df

But there is clearly data, and the reason for the high probability is that there is sheetnamea problem with (the name of the table).

Then try other methods:

The figure below is the header of Excel, with a total of 115 rows of data.

Method 1: Use usecols

#获取字段的第一种写法
import pandas as pd
df=pd.read_excel('../05DataMineML/2022STU(1).xlsx',usecols=['学号','姓名','20220101','20220125','20220202','20220208','20220213','20220220','20220226','20220311','20220320','20220327','20220403','randscore'],index_col='姓名',sheet_name='2022STUMOOC')
df.info()

index_col: specify the index value as the table
usecols: pandas reads excel Use the usecols parameter in read_excel() to read the specified column
sheet_name: table name

Important: To use the usecols parameter, sheet_name must be written explicitly.

Method 2: Use numpy

#获取字段的第二种写法:使用numpy
import pandas as pd
import numpy as np
df=pd.read_excel('../05DataMineML/2022STU(1).xlsx',converters={
    
    '学号':str},usecols=np.arange(3,16),index_col='姓名',sheet_name='2022STU')
df.head()

Converters are involved here:

converters={'学号':str}: Convert the student number to a character type for subsequent operations.

used hereusecols=np.arange(3,16)

Method 3: Use slice interval

#获取字段的第三种写法:切片区间
import pandas as pd
import numpy as np
df=pd.read_excel('../05DataMineML/2022STUMOOC (1).xlsx',converters={
    
    '学号':str},usecols=("D:P"),index_col='姓名',sheet_name='2022STUMOOC')
df

It is used here usecols=("D:P"), that is, the serial number value of each column in the following figure is used for slicing

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Summarize:

• converters usage: conversion type. For example, change a column of Excel data from int to str
• usecols usage:
• 1. usecols=['student number','name']
• 2. usecols=np.arange(3,16)
• 3. usecols=(“D:P”)