将dtype=object numpy数组保存在包含浮点值和字符串的csv文件中

Question

我必须在CSV文件的每行中保存3个字符串和一个浮点值。以下是我所做的：

filename = "results.txt"
if os.path.exists(filename):
append_write = "a"
else:
append_write = "w"

#I am saving 3 strings and one float, they come from a numpy array 
results = np.array(["a", "b", "c", 0.32],dtype=object)

f = open(filename, append_write)
np.savetxt(f, results, delimiter=",")
f.close()

然而，每当我运行这样的代码时，就会出现以下错误

raise TypeError("Mismatch between array dtype ('%s') and "
TypeError: Mismatch between array dtype ('object') and format specifier ('%.18e')

如何将NumPy数组中的混合变量保存到CSV文件中？

Answer 1

您想要为np.savetxt指定一个fmt字符串，如下所示：

results = np.array(["a", "b", "c", 0.32], dtype=object).reshape(1, -1)
fmt = '%s,%s,%s,%f'
with open(filename, append_write) as f:
np.savetxt(f, results, delimiter=",", fmt=fmt)

N。B.你似乎想按行追加数据，在这种情况下，你需要重新整形才能将数据分成列(一行(。fmt字符串应与要指定的列数相匹配。