[英]Deleting Rows in a .csv File (Python)
Good evening, I'm having a problem with a code I'm writing, and I would love to get advice.晚上好,我正在编写的代码有问题,我很想得到建议。 I want to do the following:
我想做以下事情:
The file I'm working with is large (12.2 GB, 87 million rows), and has 6 columns within it, with the first 5 columns being numerical values, and the last value containing text.我正在处理的文件很大(12.2 GB,8700 万行),其中有 6 列,前 5 列是数值,最后一个值包含文本。
Here is my code:这是我的代码:
import csv
directory = "/media/gman/Folder1/processed/test_removal1.csv"
with open('run1.csv', 'r') as fin, open(directory, 'w', newline='') as fout:
# define reader and writer objects
reader = csv.reader(fin, skipinitialspace=False)
writer = csv.writer(fout, delimiter=',')
# write headers
writer.writerow(next(reader))
# iterate and write rows based on condition
for i in reader:
if (i[-1]) == -3.4028E38:
writer.writerow(i)
When I run this I get the following error message:当我运行它时,我收到以下错误消息:
Error: line contains NUL
错误:行包含 NUL
File "/media/gman/Aerospace_Classes/Programs/csv_remove.py", line 19, in <module>
for i in reader: Error: line contains NUL
I'm not sure how to proceed.我不知道如何继续。 If anyone has any suggestions, please let me know.
如果有人有任何建议,请告诉我。 Thank you.
谢谢你。
I figured it out.我想到了。 Here is what I ended up doing:
这是我最终做的:
#IMPORT LIBRARIES
import pandas as pd
#IMPORT FILE PATH
directory = '/media/gman/Grant/Maps/processed_maps/csv_combined.csv'
#CREATE DATAFRAME FROM IMPORTED CSV
data = pd.read_csv(directory)
data.head()
data.drop(data[data.iloc[:,2] < -100000].index, inplace=True) #remove rows that contain altitude values greater than -100,000 meters.
# this is to remove the -3.402823E038 meter altitude values that keep coming up.
#CONVERT PROCESSED DATAFRAME INTO NEW CSV FILE
df = data.to_csv(r'/media/gman/Grant/Maps/processed_maps/corrected_altitude_data.csv') #export good data to this file.
I went with pandas to remove rows based on a logic argument, this made a dataframe.我和熊猫一起根据逻辑参数删除了行,这构成了一个数据框。 I then exported the dataframe into a csv file.
然后我将数据框导出到一个 csv 文件中。
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