python讀檔

我上週真正開始測試python的程式碼，目前最先碰到的是讀檔的部分．

幾乎要用的每個步驟都要查找，不過也總算讓我解決了問題． 之後的文章要來處理如何精熟畫圖以及python的分析模式

狀況：

我現在有三份文字檔，裡面都記錄我的rgb訊號，分別放在不同的資料夾中，必須要將他們依序讀出並且轉成我得的資訊並畫圖

問題：

1. 因為python本身讀檔方式是看.py檔在哪，就讀去同層裡的檔案，但是我必須要分別在不同資料夾中讀取，所以勢必要去告訴電腦路徑的修改

2. 因為每個檔案名稱都不同，只有附檔名是一樣的，所以要學會模糊比對（這邊學到的是正則表達式）

3. 文字檔裡面如何去篩選我要的資訊並把他們轉成字串

4. 如何做到像matlab一樣ｈold on 畫圖

?、

import os

import re

import numpy as np

for i in range (0,3):

    path = "/Users/bobobo746/Desktop/signal_test/" + "%s" %i

    # 先設置我之後要讀的路徑位置. 而i就是照片裡的資料夾名稱0,1,2

    retval = os.getcwd()

    # os.gercwd 是要先找出當前的路徑

    print "Current root: " ,retval

    os.chdir( path )

    #chdir ：ｃhange Directory

    retval = os.getcwd()

    print "Successfully change root:  %s" % retval

再來就是要如何在資料夾中找到我需要的檔案呢？ 就要利用os.walk來遍歷資料夾內所有的檔案

裡面提到walk會帶出一個我當下位置所包含的東西（list），當中包含了root(根目錄),dirs(資料夾)還有files(檔案），把他們print出來確認：

for root, dirs, files in os.walk(retval):

    print "root: "+(root)

    print "dirname: %s" %(dirs)

    print"filesnames: %s " %(files)

做模糊比對，至於正則表達式的原理我之後再補上免得久了又忘掉：

s = r'\.txt'

# \. 反斜線是要取消.（點）在正則表達式的特殊含義，回歸成單純反斜線的符號

for ii in range(len(files)):  

# Use len() to get how many files in folder

    t = re.search(s,files[ii])

    if bool(t):

        print  "File:%s" %files[ii] +" is read"

下面是開始讀取訊號的部分：

       filename = files[ii]

            pos = []

            with open(filename, 'r') as file_to_read:

                lines = file_to_read.readlines()

                #readlines是讀取每行

            p_tmp = [str(i) for i in lines]

            # 讀到的都當成list格式放在p_temp

            wow = np.append(pos,p_tmp)

            # 再把他們集結

            wow = np.array(wow)

            # 轉成陣列，因為每行讀去問題,\n的字樣會出現之後便成字串會消不掉

            #,所以要先轉成陣列再利用rsrip消除 最right的： \n

            len (wow)

            wow_no_slash =[]

            for i in range(0,24000,1):

                temp = wow[i].rstrip()

            #strip是消除空白或是\n等符號，ｒ是右邊 ,l就是左邊

                wow_no_slash = np.append(wow_no_slash,temp)

            wow_no_slash

 

            print wow_no_slash[51]

 

            find_R = 'Reaction_R:'

            find_G = 'Reaction_G:'

 

            l_list = wow_no_slash.tolist()   

            # index is a function in list , so numpy.array needs to Transform to l_list

            l_list.index(find_R)

            l_list.index(find_G)

            #print l_list[52]

            #print l_list[2888]

            Signal_R = l_list[52:l_list.index(find_G)-1]

            print Signal_R

            len(Signal_R)

 

            import matplotlib.pyplot as plt

            plt.plot(Signal_R, 'r')

           

# End read signal

    parent_path = os.path.abspath("..") 

    # Back to upper layer folder

    print parent_path

plt.show()

# plt在最後放 ＝ｈold on

以下是完整原始碼：

import os

import re

import numpy as np

for i in range (0,3):

    path = "/Users/bobobo746/Desktop/signal_test/" + "%s" %i     #i in here is named as file name

    retval = os.getcwd()

    print "Current root: " ,retval

    os.chdir( path )

    retval = os.getcwd()

    print "Successfully change root:  %s" % retval

    for root, dirs, files in os.walk(retval):

        print "root: "+(root)

        print "dirname: %s" %(dirs)

        print"filesnames: %s " %(files)

    s = r'\.txt'

    for ii in range(len(files)):   # Use len() to get how many files in folder

        t = re.search(s,files[ii])

        if bool(t):

            print  "File:%s" %files[ii] +" is read"

# Start to read signal:

            filename = files[ii]

            pos = []

            with open(filename, 'r') as file_to_read:

                lines = file_to_read.readlines()

            p_tmp = [str(i) for i in lines]

            wow = np.append(pos,p_tmp)

            wow = np.array(wow)

            len (wow)

            wow_no_slash =[]

            for i in range(0,24000,1):

                temp = wow[i].rstrip()

                wow_no_slash = np.append(wow_no_slash,temp)

            wow_no_slash

            print wow_no_slash[51]

            find_R = 'Reaction_R:'

            find_G = 'Reaction_G:'

            l_list = wow_no_slash.tolist()    # index is a function in list , so numpy.array needs to Transform to l_list

            l_list.index(find_R)

            l_list.index(find_G)

            #print l_list[52]

            #print l_list[2888]

            Signal_R = l_list[52:l_list.index(find_G)-1]

            print Signal_R

            len(Signal_R)

            import matplotlib.pyplot as plt

            plt.plot(Signal_R, 'r')

            #plt.show()

# End read signal

            print "\n"

        else:

            print "nothing"

    parent_path = os.path.abspath("..")   # Back to upper layer folder

    print parent_path

plt.show()

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