condition_mask=tf.not_equal(x,tf.constant(-1.))
    partitioned_data = tf.dynamic_partition(
        x, tf.cast(condition_mask, tf.int32) , 2)
    partitioned_data[1] = partitioned_data[1] + 1.0
    condition_indices = tf.dynamic_partition(
        tf.range(tf.shape(x)[0]), tf.cast(condition_mask, tf.int32) , 2)
    x = tf.dynamic_stitch(condition_indices, partitioned_data)
    # Here x=[1.1, -1., 6.2, 5.3, -1, 8.4], the -1. values remain