在csv中過濾特定行，記錄上一個值

我已經有了一個具有不同數據格式的.csv文件，我試圖使用同一列上的值進行操作。在csv中過濾特定行，記錄上一個值

我的csv文件是這樣的：

"int","float","stirng", more data

例子：

"2","1.378","Johnny" 
"1","1.379","Walker" 
"5","1.380","Jack" 
"8","1.700","Daniels" 
"8","1.710","Baileys" 
"8","1.381","Monkey" 
"8","1.711","Shoulder" 
"8","1.383","Captain" 
"8","1.385","Morgan" 
"8","1.392","Drinks" 
More rows

我想在第二列減去值，如果它們的區別在於> X。（只有那些，我不在乎別人）。

我迄今爲止代碼：

with open ('input.csv', 'r') as file, open ('output.csv', 'w') as f_out: 
    readCSV = csv.reader(file) 
    writeCSV = csv.writer(f_out, lineterminator='\n') 
    last = None 

    for row in readCSV: 
     datalat = float(row[1]) 

     if last is not None: 
      #print("difference -> %f" %(datalat-last)) 
      outp = (datalat-last) 
      if outp <= 0.02: 
       writeCSV.writerow(row) 
      last = datalat

輸出看起來像：

5,1.380,Jack 
8,1.710,Baileys 
8,1.381,Monkey 
8,1.383,Captain 
8,1.385,Morgan 
8,1.392,Drinks

但我想它是：

"2","1.378","Johnny" 
"1","1.379","Walker" 
"5","1.380","Jack" 
"8","1.381","Monkey" 
"8","1.383","Captain" 
"8","1.385","Morgan" 
"8","1.392","Drinks"

所以應該做的是隻寫入行數小於0.02的差異，如果有一個差異較大的行丟棄它，然後比較下一行到la st書寫的行，而不是最後一個被丟棄的行。

來源

2017-06-07 David

你不更新'last'隨時隨地 –

@MosesKoledoye對不起，我錯過了線，而複製我的代碼。更新。 – David

兩件事情：

你應該（用abs）的區別，你不知道先驗其中兩個較大取絕對值。
如果條件滿足，只更新last，所以last永遠不會被丟棄。

last = float(next(readCSV)[1]) # assign first reference value 
f_out.seek(0)     # return to start of file 
for row in readCSV: 
    datalat = float(row[1]) 
    diff = abs(datalat-last) 
    if diff <= 0.02: 
     writeCSV.writerow(row) 
     last = datalat

來源

2017-06-07 15:33:46

工程就像一個魅力。謝謝您的意見！ – David

在csv中過濾特定行，記錄上一個值

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