pandas で csv の読み書き

csv の作成

csv_create.py

#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#   csv_create.py
#
#                   Oct/01/2018
# ------------------------------------------------------------------
import sys
import pandas as pd
#
# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
df = pd.DataFrame([
        ["t1271","千葉",59476,"2003-9-21"],
        ["t1272","勝浦",49573,"2003-3-14"],
        ["t1273","市原",29471,"2003-6-25"],
        ["t1274","流山",39872,"2003-8-28"],
        ["t1275","八千代",27176,"2003-10-5"],
        ["t1276","我孫子",13175,"2003-1-15"],
        ["t1277","鴨川",85134,"2003-12-21"]])

print(df)
#
path="./cities.csv"
#
df.to_csv(path,header=None,index=None)
#
sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

次の csv が作成されます。

cities.csv

t1271,千葉,59476,2003-9-21
t1272,勝浦,49573,2003-3-14
t1273,市原,29471,2003-6-25
t1274,流山,39872,2003-8-28
t1275,八千代,27176,2003-10-5
t1276,我孫子,13175,2003-1-15
t1277,鴨川,85134,2003-12-21

csv の読み込み

csv_read.py

#! /usr/bin/python
# -*- coding: utf-8 -*-
#
#   csv_read.py
#
#                   Oct/01/2018
# ------------------------------------------------------------------
import sys
import pandas as pd
#
# ------------------------------------------------------------------
sys.stderr.write("*** 開始 ***\n")
#
file_csv = "./cities.csv"
#
df=pd.read_csv(file_csv,header=None)
print(df)
print(df.head())
#
df.to_csv("tmp001.csv",header=None,index=None)
sys.stderr.write("*** 終了 ***\n")
# ------------------------------------------------------------------

実行結果

$ ./csv_read.py 
*** 開始 ***
       0    1      2          3
0  t1271   千葉  59478  2003-9-21
1  t1272   勝浦  49573  2003-3-14
2  t1273   市原  29179  2003-6-25
3  t1274   流山  39872  2003-8-28
4  t1275  八千代  29176  2003-10-5
5  t1276  我孫子  29176  2003-10-5
6  t1277   鴨川  29176  2003-10-5
       0    1      2          3
0  t1271   千葉  59478  2003-9-21
1  t1272   勝浦  49573  2003-3-14
2  t1273   市原  29179  2003-6-25
3  t1274   流山  39872  2003-8-28
4  t1275  八千代  29176  2003-10-5
*** 終了 ***