Python：将数据写入csv文件

Question

Coming from Matlab to Python, so I am a bit confused.

I have a script which calculates Wave Period, Wave Number, Wave Height and RAOs for a number of runs. For example are the RAO arrays created like this in a loop:

# Calculation of RAO

rao_2[j] = sway[j]/wave[j]
rao_3[j] = heave[j]/wave[j]
rao_4[j] = roll[j]/(k[j]*wave[j])

I want to save all the information in a CSV file where I want the rows to be each run and the columns are 'Period', 'Wave Number', 'Wave', 'RAO' etc.

I have tried to use the following method:

prelim_data = list(zip(T, k, wave, wave_front, wave_back, rao_2, rao_3, rao_4))

df = pd.DataFrame(data=prelim_data, columns=['Period', 'Wave Number', 'Wave', 'Front Wave', 'Back Wave', 'RAO 2', 'RAO 3', 'RAO 4'])

df.to_csv(pre_fid1, index=False, header=False)

But this seems to write it all into one list in one column, which isn't a too big of a deal. But the problem arises when I want to combine the five CSV files from five different runs into one big one.

They have different amount of rows but the same amount of columns, but when I combine them like this:

import pandas as pd

pieces = []

for num in [8, 9, 10, 11, 12, 13, 14, 15]:
    s = pd.read_csv('main/prelim_results%d.csv' % num, header=1)
    print('Reading Number: ', num)
    print(s.loc[0][0])
    pieces.append(s)

newcsv = pd.concat(pieces, axis=0)
newcsv.to_csv('main/prelim_main.csv', index=0, header=0)

data = pd.read_csv('main/prelim_main.csv', header=None)

The first CSV file is written into the first row.. What am I doing wrong?

Is there a better way to save my data and combine it into one file?

Thanks for any help

Answer 1

Try below code :

import pandas as pd
pieces = []
for num in range(8,16):
    s = pd.read_csv('main/prelim_results%d.csv' % num)
    print (s.head())
    print('Reading Number: ', num)
    pieces.append(s)
newcsv = pd.concat(pieces, axis=0)
newcsv.to_csv('main/prelim_main.csv', index=0, header=0)
data = pd.read_csv('main/prelim_main.csv', header=None)
print (data.head())