CSV的讀取與寫入
csv是常用的資料格式，因為是純文字檔操作方便，python可以使用csv模組來存取csv
| 函數 | 說明 |
|---|---|
| csv.reader(檔案) | 產生讀取csv物件，讀取形式為串列 |
| csv.writer(檔案) | 產生寫入csv物件，讀取形式為串列 |
| csv.DictReader(檔案) | 產生讀取csv物件，讀取形式為字典 |
| csv.DictWriter(檔案) | 產生寫入csv物件，讀取形式為串字典 |
| csv物件.writeheader() | 把定義好的欄位(fieldnames=)寫進去檔案 |
| csv物件.writerow | 寫入一維串列或字典 |
| csv物件.writerows | 寫入二維串列或字典 |
下面四種方式可選擇一種方式建立csv
記得把模式”a”改成自己想要的
import csv
#第一種
with open("test3.csv", "w",encoding="utf-8-sig", newline="") as csvfile:
#加入BOM用excel才不會亂馬
name = ['number', 'name', 'Sit-ups(1m)', 'Push up(1m)', '3KM']
#預先欄位
writer_in = csv.DictWriter(csvfile, fieldnames=name)
#定義欄位名稱
writer_in.writeheader()
#把欄位名稱寫入csv裡
writer_in.writerow({'number': "001", 'name': 'Jeff', 'Sit-ups(1m)' : "50", "Push up(1m)" : "70", "3KM" : "12min"})
#寫入一維串列
writer_in.writerow({"number" : "002", "name" : "Alleb", "Sit-ups(1m)" : "60", "Push up(1m)" : "60", "3KM" : "16min"})
writer_in.writerow({"number" : "003", "name" : "Joe", "Sit-ups(1m)" : "40", "Push up(1m)" : "50", "3KM" : "13min"})
csvfile.write("--------no1--------")
#依照字典值把元素帶進去
#第二種
with open("test3.csv", "a" ,encoding="utf-8-sig", newline="") as csvfile:
writer_in = csv.writer(csvfile)
writer_in.writerow(["number", "name", "Sit-ups(1m)", "Push up(1m)", "3KM"])
writer_in.writerow(["001", "Jeff", "50", "70", "12min"])
writer_in.writerow(["002", "Allen", "60", "60", "16min"])
writer_in.writerow(["003", "Joe", "40", "50", "13min"])
csvfile.write("--------no2-------")
#每筆資料逐筆寫入
#第三種
datalist = [
["number", "name", "Sit-ups(1m)", "Push-up(1m)", "3KM"],
["001", "Jeff", "50", "70", "12min"],
["002", "Allen", "60", "60", "16min"],
["003", "Joe", "40", "50", "13min"]
]
with open("test3.csv", "a", encoding="utf-8-sig", newline="") as csvfile:
writer_in = csv.writer(csvfile)
writer_in.writerows(datalist)
csvfile.write("--------no3--------")
#寫入二維串列
#第四種
#先建字典
datadict = [
{"number" : "001", "name" : "Jeff", "Sit-ups(1m)" : "50", "Push up(1m)" : "70", "3KM" : "12min"},
{"number" : "002", "name" : "Allen", "Sit-ups(1m)" : "60", "Push up(1m)" : "60" , "3KM" : "16imn"},
{"number" : "003", "name" : "Joe", "Sit-ups(1m)" : "40", "Push up(1m)" : "50", "3KM" : "13min"}
]
with open("test3.csv", "a", encoding="utf-8-sig", newline="") as csvfile:
#定義欄位
names = ['number', 'name', 'Sit-ups(1m)', 'Push up(1m)', '3KM']
#將dictionary寫入檔案並使用定義好的標題欄位(names)
writer_in = csv.DictWriter(csvfile, fieldnames=names) #定義欄位名稱
writer_in.writerows(datadict) #寫入字典，須以list包住字典
writer_in.writeheader() #寫入欄位名稱(第一列)
csvfile.write("--------no4(end)--------")